This adds support for breakpoints statistics

Fixes #247

Additionally removes test code / html / txt / etc from vendor dir.

Embedded structs are encoded in DWARF as fields with
package-qualified names.  They define an anonymous field
on the struct with the non-qualified name, as well as
promoted fields for each field of the embedded struct so
long as these are not shadowed by fields of the containing
struct.

Fixes #220.

I encountered the error message described in the issue while debugging
InfluxDB. I can confirm that after this fix the error disapeared.

Fixes #258

<esc>[0m (reset) should be used instead of <esc>[37m (set foreground
color to white)

/proc/pid/stat needs more complex parsing

Fixes #239

If an optional linespec argument is passed to clearall command then only
breakpoints matching this linespec will be cleared.

Behavior of clearall command without arguments hasn't changed.

The 'source' command reads the file specified as argument and executes
it as a list of delve commands.
Additionally a flag '--init' can be passed to delve specifying a file
containing a list of commands to execute on startup.

Issue #96

Fixes #257

g.SP refers to the frame the goroutine was in the last time it was
scheduled out. Instead of calling proc.(*Process).stacktrace directly
we should call proc.(*Process).GoroutineStacktrace that substitutes
fresh values retrieved from thread registers when necessary.
This bug leads to occasional problems with `next`.

Use godeps to vendor dependencies and the normal go toolchain, with
GO15VENDOREXPERIMENT=1 set to properly vendor dependencies for reproducible
builds.

Fixes #220

Support for dumb terminal

Fixes #252

set <variable name> <value>

Refactored variables.go to separate calculation of a variable's address from
reading its value. This change is useful to implement the 'set' command
as well as the evaluation of more complex expressions (in the future).

During process termination we seem to receive notifications of new
threads that die before we can add them, ignore them

Instead of using PTRACE_DETACH to inject SIGINT into the tracee use
sys.Kill directly: PTRACE_DETACH is allowed to ignore its signal
argument if the tracee isn't in signal-delivery-stop status.

Only use software breakpoints for now. The reasoning is because it
complicates the code without justification, and is only supported on
Linux. Eventually, once watchpoints are properly implemented we will
revive some of this code. Also, if it is ever necessary to actually set
a hw breakpoint we can revive that code as well.

All future versions of this code will include support for OSX before
being merged back in.

Previously, 'ldflags' were added to the compiler invocation based on the
version of Go the user was running. It seems to make more sense to
simply always pass along the flags on Darwin (due to the bug mentioned
in the comment above this line in the diff) as that is less brittle than
branching on the Go version, and yet will not break current users /
developers work flow.

Use proc.(*Process).FindGoroutine in proc.(*Process).SwitchGoroutine and
debugger.(*Debugger).Stacktrace. That method did not exist when those
were originally written.

Be more tolerant of unitialized memory, limit length of strings like we
do for array/slices.

Workaround for Issue #189

Replace function with a stdlib implementation.