Renames obs_output_canpause to obs_output_can_pause

Check to make sure the texrenders and textures on a source are valid
before destroying.

Adds warnings for graphics functions to ensure that graphics functions
are called within an active graphics context, and add warnings if
required pointer parameters are null.

Uses obs_source_valid in data_valid which will ensure a debug message is
displayed if null.

To prevent confusion with the new obs_source_valid function which
displays a warning, rename the "source_valid" function to "data_valid"
to emphasize that it's checking for the validity of the internal data as
well as the source itself.

API removed:
--------------------
gs_effect_t *obs_get_default_effect(void);
gs_effect_t *obs_get_default_rect_effect(void);
gs_effect_t *obs_get_opaque_effect(void);
gs_effect_t *obs_get_solid_effect(void);
gs_effect_t *obs_get_bicubic_effect(void);
gs_effect_t *obs_get_lanczos_effect(void);
gs_effect_t *obs_get_bilinear_lowres_effect(void);

API added:
--------------------
gs_effect_t *obs_get_base_effect(enum obs_base_effect effect);

Summary:
--------------------
Combines multiple near-identical functions into a single function with
an enum parameter.

(Jim) The documentation for glXChooseFBConfig states that the last value
of the visual attributes array must be 'None'.  Fixes potential
initialization issues with certain drivers.

Closes jp9000/obs-studio#486

Meant as a part of solving mantis issue 105 ("Disk space usage monitor
when recording").

From pull request: jp9000/obs-studio#374
Relevant mantis issue: https://obsproject.com/mantis/view.php?id=105

From pull request: jp9000/obs-studio#374

These functions resolve the absolute path from a relative path.

Use explicit UTF-8 byte sequence for the "no-break space" character.

Prevents issues with certain editors, and fixes the following compiler
warning on Visual C++:

warning C4819: The file contains a character that cannot be represented
in the current code page (X). Save the file in Unicode format to prevent
data loss

Use explicit UTF-8 byte sequence for the "no-break space" character.

Prevents issues with certain editors, and fixes the following compiler
warning on Visual C++:

warning C4819: The file contains a character that cannot be represented
in the current code page (X). Save the file in Unicode format to prevent
data loss

Use explicit UTF-8 byte sequence for the "no-break space" character.

Prevents issues with certain editors, and fixes the following compiler
warning on Visual C++:

warning C4819: The file contains a character that cannot be represented
in the current code page (X). Save the file in Unicode format to prevent
data loss

(Jim) For some reason a character outside of the standard ASCII
character set was used in this source file.  "Eight Spoked Asterisk",
Unicode character 0x02733.  Non-ASCII characters should probably not be
used directly in source files due to potential character encoding
issues that can occur depending on the operating system and compiler.

Closes jp9000/obs-studio#485

rtmp-services: Remove unnecessary iNSTAGIB.tv entry

iNSTAGIB.tv and Vaughn Live share the same ingestion system. Having
this entry is therefore unnecessary.

This replaces the name-based detection of the 4K intensity pro, and
allows other devices to be able to use the BGRA pixel format, if the
user so chooses.

It's possible for one signal handler to disconnect another during signal_handler_signal, which could result in crashes when the disconnected signal handler is called with a potentially freed data pointer due to other cleanup.

Detected by Coverity Scan (CID 12876, 12877, 12878, 12879)

Detected by Coverity Scan (CID 12831, 12830)

Another thread could be manipulating the active_log_contexts array while the current thread is trying to read it, resulting in an uninitialized memory crash as the da_push_back call was not protected by the mutex.

Detected by Coverity Scan (CID 12856)

Note: This functionality should probably be considered as a temporary
solution.  Ideally, sources should not be visible on creation until the
user presses "OK" in the initial properties dialog.  Also, the problem
of initial visibility can additionally be solved by implementing the
preview/program functionality.  Once preview/program is implemented the
need for this patch will be negated, and the option should probably be
removed.

Closes jp9000/obs-studio#483

Polls for file changes like the text plugin does.  This is an interim
solution; both the text plugin and image source should use a file
monitoring API, preferably implemented through libobs.

Closes jp9000/obs-studio#482

In case a system authentication prompt is open the actual error code
(via err_get_code) is kIOReturnExclusiveAccess on OSX 10.9; I'm not
100% sure if this makes the "if (!value)" part of the code obsolete,
but that code path shouldn't be triggered under most circumstances
anyway

Fixes https://obsproject.com/mantis/view.php?id=346

When using a text file with the source and the font face is changed, it
would cause it to fail to update the glyphs and text accordingly.  It
would trigger an error jump at line 392 of text-freetype2.c, ultimately
resulting in the text to render garbled after that.

How to reproduce:
Set the source to get text from a file, then just change the font face
(but not the size or anything else).

When updating text from file periodically, newer glyphs that weren't
already cached would not end up being rendered.  This fixes the issue by
calling cache_glyphs after the file has been updated.

How to reproduce the original issue:
Set a text-freetype2 source to load an english-only text file.  Then
overwrite the text in the file with non-english characters.  The
non-english characters will then fail to render.

Reported at https://obsproject.com/mantis/view.php?id=336

Closes jp9000/obs-studio#481

This variable needs to be the same size for both architectures.  size_t
is 8 on 64bit and 4 on 32bit.