Fix docs.

Converting RUN_TEST() from a macro to a function significantly reduces the size
of the compiled binary.  On amd64, the largest test runner in the test suite
(testsample_DefaultsThroughCommandLine_runner.o) was reduced from 3.4 kB to 2.4
kB (stripped).

- Tweak a couple style problems with Ruby scripts.

- Running time macros have been made more portable, previously it was not
  possible to override all macros
- Running time macros will be executed by default test runner, and auto test
  runners
- Adds a default execution time implementation for unix. (Previous default
  implementation only worked on Windows)
- For embedded platforms there is a simple method of getting a default
  implementation by defining a single macro UNITY_CLOCK_MS()
- Removed need for UNITY_EXEC_TIME_RESET. This was not being used for the default
  implementations, if anything ever did need reset-like functionality it could
  simply be wrapped up with the start or stop macros for that platform

This allows multiple groups to be compiled into the same executable by naming each function uniquely.

Adds support for :mock_suffix when generating mock setup and teardown
functions. Also documents both prefix and suffix in the helper script
guide.

Auto generated test runner should generate a code  which includes
setjmp.h only if UNITY_EXCLUDE_SETJMP_H is not defined

- Enable support for Green Hills Software compiler
- Define weak implementations only once except on Windows

MinGW supports a limited form of weak symbols, with the restriction
that weak/default implementations need to be defined in the same
translation unit they are called from.  Strong/overriding symbols
may of course be specified in a different translation unit.

This is simpler and more flexible than embedding C code in the Ruby options
(:suite_setup and :suite_teardown).  However, support for :suite_setup and
:suite_teardown is kept for backwards compatibility.

Several configurations are possible:
1. :suite_setup and :suite_teardown options provided and used.
2. :suite_setup and :suite_teardown options not provided (nil):
  2a. Weak symbols not supported; suiteSetUp() and suiteTearDown() are not called.
      It would be simpler to make user-provided functions mandatory in this case,
      but it could break some pre-existing test suites.
  2b. Weak symbols are supported and the stub implementations of suiteSetUp() and
      suiteTearDown() are called if there are no user-provided functions.
  2c. Weak symbols are supported but overridden by user-provided suiteSetUp() and
      suiteTearDown() functions.

Starting to enforce our coding style. The first step is that we’ve pulled in Rubocop to check out Ruby syntax. There is likely a bit of customization to do yet AND there is definitely that backlog of todo’s that we just told it to ignore.

Added ability to inject defines, much like what was built into Ceedling before Ceedling switched to just using this generator.