Add --windows option to bootstrap.py

Makes it possible to make a native Windows build when using Cygwin Python.
browse: Read ninja's error text from stderr.
Add python ninja_syntax.py support for pool
Add ninja.vim syntax for pool
Add missing rspfile and rspfile_content
Add pool
Add missing default keyword
Merge pull request #473 from riannucci/fix_emacs

Fix emacs ninja-mode
Merge pull request #472 from riannucci/add_python_pool_syntax

Add python ninja_syntax.py support for pool
Merge pull request #471 from riannucci/fix_vim_syntax

Fix vim syntax
NINJA_STATUS: add support of `%p` for percentage
Update version number in ninja.vim after recent changes.
Merge pull request #475 from nico/vim

Update version number in ninja.vim after recent changes.
Merge pull request #474 from yannicklm/master

 	NINJA_STATUS: add support of `%p` for percentage
update a comment
correctly open /dev/null in subprocesses

Fixes issue #468.
wrap test in anon namespace
fix test build under clang/system gtest

Tests always need GTEST_HAS_RTTI=0 set, but the code was only
setting it in the --with-gtest branch.  Instead always use the
test-specific cflags when compiling test code.
ninja_syntax.py: don't add trailing space when build has no inputs

Seen in Ninja's configure.py where it creates an "rpmbuild" command.
Merge pull request #467 from ppuryear/browse-error

browse: Read ninja's error text from stderr.