MAKE: ask gnulikes to warn and be pedantic + fixes

It seems clang 3.4 thinks the codebase is in fantastic shape and gcc 4.9.0
has only minor niggles, which I fixed:

- fix uninitialized member warning:
    In DEBUG mode the expr member doesn't get properly initialized to NULL.

- fix warnings about directive inside of macro's:
    On some platforms/compilers, sprintf is a macro. Putting macro directives
    inside of a macro is unportable and gcc 4.9 warns about that.

- fix signed vs. unsigned comparison warning:
    The in-memory table will luckily not even come close to the limits imposed
    by ssize_t. If it ever reaches that, we've got bigger problems.
Added a types.h with vim.h unsigned int typedefs.
Extract file_search.c from misc2.c

Continue to split misc2.c in many other files (see #209).

The only changed I made to the moved code was adding
`vim_free(ff_expand_buffer)` to `free_finfile()`. This is was needed
because `ff_expand_buffer` was moved from `misc2.c` to `file_search.c`.
CONTRIBUTING.md: mention coding style
Use $(MAKE) instead of ${MAKE}, and fixup two more make invocations.

Include a new SINGLE_MAKE which can be used to invoke make but using
only a single job, and in way that avoids any warnings from make.
Use SINGLE_MAKE to execute the tests, since they're meant to be run
serially.

Also, prefer the use of $(MAKE) to avoid invoking an extra subshell
(saves some time).
Clean-up main.c: follow STRNICMP replacement.
Be more explicit about OS X deps installation
Adding darwin platform to common.sh build script
README.md: remove lingering references to sha1sum in OSX instructions
Fixed nvim homebrew formula

I now also do make install
homebrew: deparallelize build
Remove __ARGS macro. Close #205

This is a squash of all commits sent to #81.

- Remove unused undef of __ARGS.
- Fix mch_rename declaration.
- Follow changes related to moved & extracted files.
- Properly indent function declarations of getchar.h and quickfix.c.
Use -Werror.

This makes all warnings errors. We don't want any warnings, so we should
enforce that.
Make Travis compile on GCC and Clang.
Add unit tests for ported filesystem functions.
Remove dead stack-checking code.

Code under HAVE_STACK_LIMIT is not used.
The definition was commented out in rev 180 of the original
Mercurial repo, and then completely removed in rev 2520,
but the code guarded by it was left in.
Remove traces of old custom undo memory manager.

There were two memory management implementations,
standard malloc-based, and a custom allocator.

Removed in rev 2230 in the Mercurial repo.
Move some of misc1.c to indent.c.

My little contribution to #209.
README.md: Fixed brew install instructions
Anchor gitignore paths

This makes the intention more explicit and avoid any accidental
matching elsewhere in the tree.

Conflicts:
	.gitignore