Fix codegen for GLSL casts.

Codegen_C generally expects "id" to be a variable name; the previous code just
happened to work in a number of simple cases.
Merge pull request #410 from halide/glsl_fix_casts

Fix codegen for GLSL casts.
Fix build issue for camera_pipe
Merge branch 'master' of github.com:halide/Halide
Track trunk pnacl llvm again
Fix a bad bug in memoization cache where buffer memory was not freed
properly. (Wrong pointer was passed to halide_free, which was almost
always ok as it turned into a free of NULL.)

Improve cache debugging printfs to write key as one printf and add a
bit more information. (halide_printf on mobile devices often results
in a log line per call. It only makes sense to call it with an entire
line.)

Move locking scopes to cover cache validation as otherwise it will
fail due to race conditions in parallel filters. (Only applies when
CACHE_DEBUGGING is turned on.)
Fix formatting, remove tabs.
Fix a bug in dynamic stage skipping where predicates that depend on an
allocation can be moved outside the allocation. Causes compilation
failures via looking up an undefined chace_key symbol in some cases
with Memoization and dynamically skippable realizations.
Bring Python bindings build up to date
Merge pull request #415 from fcr/master

Bring Python bindings build up to date
Typo fix.
bug423: Add dependencies to the libHalide.a libtool command line for the CMake/Xcode build
Merge pull request #424 from halide/bug423

bug423: Add dependencies to the libHalide.a libtool command line for the...
rename README to README.md so that the github can render it correctly
Merge pull request #427 from guanqun/master

rename README to README.md so that the github can render it correctly
Update make distrib for README.md

`make distrib` was looking for the non-existent file "README", which was renamed to "README.md" by commit 9fc6c65
Merge pull request #433 from Dr-Emann/patch-1

Update make distrib for README.md
Add include for msvc 2010 (fixes #428)
Merge branch 'master' into runtime_linkage_cleanup

Conflicts:
	src/runtime/cache.cpp