Testing the public interface mch_can_exe should suffice. Every former
test of is_executable has a counterpart in the tests of mch_can_exe.
Thus we can keep private things private.
* removed a putenv() implementation which isn't needed anymore
* mch_getenv() and mch_setenv() are now functions in src/os/env.c
* removes direct calls to getenv() and setenv() outside of src/os/env.c
* refactored the logic of get_env_name into mch_getenvname_at_index
* added unittests for the functions in os/env.c
* Rename mch_full_name to mch_get_absolute_path.
* Rename mch_is_full_name to mch_is_absolute_path.
* Add a lot of missing parentheses.
* Remove yoda-conditions for consistency.
* Remove spaces in function declaration.
* Rename mch_FullName to mch_full_name to match the style guide.
* Add mch_full_dir_name, which saves the absolute path of a given
directory relative to cwd into a given buffer.
* Add function append_path, which glues together two given paths with a
slash.
* Adapt moonscript coding style to the tests.
Tests will be written using the [moonscript](http://moonscript.org/) language,
a lua 'dialect' that is whitespace-significant and has a syntax similar to
coffeescript. The test framework used is [busted](http://olivinelabs.com/busted/),
a bdd framework for lua/moonscript.
Luajit has a nice ffi module, which lets lua programs link shared libraries and
call it's functions without writing any C code.
To take advantage of this fact for testing C functions, a new target was added
to CMakeLists.txt, which compiles neovim as a shared library that is loaded by
the process running the tests.
This commit adds necessary code for downloading and installing a lua package
manager(luarocks) locally. It wasn't added as a subtree because there are quite
a few blobs in its source tree.
