Adds to a test case verifying glGetIntegerv returns
correct results when the current texture id is not TEXTURE0 and fixes
library_gl.js so that it returns correct results.
add vector support for and, or and xor
Add command line parameter --no-heap-copy that optimizes for small memory footprint and fread() performance over the default behavior that copied VFS to HEAP, that is designed for mmap() performance.

Adjust MEMFS node contentMode enum to reflect whether content is off the main HEAP or not. Note that this enum is not much used, so this has little effect. Add browser tests to check that fread() and mmap() work with and without --no-heap-copy.
CONTRIBUTING.markdown
Give names to most manually assigned functions in the .js files, in form "var x = function()" -> "function x()" so that error stack traces and profiling stack traces are more informative and do not contain anonymous functions.
add missing parens for select mathop
add testcase for select fix
getting some initial set of x86 intrinsics mapped to JS SIMD ops (earlier version with type suffixed ops and unsigned integer, to be updated); bug fix: withXu32 instead of withX for uint32x4 initialization; bug fix: splat(0) instead of zero for uint32x4 initialization
updated to use latest JS SIMD APIs