Support read/write on socket file descriptors.

Add test_websockets_bi_fileops to test using read and write instead
of recv and send respectively. Uses same source files with
USE_FILE_OPS define.
Shared file-descriptor nums for files and sockets.

Also, add FS.createFileHandle(stream) and FS.removeFileHandle
functions for adding to and removing from the streams/file-descriptor
table.
* Added symlink support.
Added a symlink testcase.
fix highp to lowp in tests
make fullscreen handling closure friendly
fix lua for native builds
prepare for lua benchmark
add lua scimark
enable lua benchmark
update lua test
run benchmarks longer with fewer reps
add lua-binarytrees benchmark
reorder benchmarks
make test runner library building more robust and enable library reloading in benchmark suite
separate lua benchmarks when saved
Issue #1172: added test_fscanf to runner.py
Issue #1172: fix for fscanf
export callMain through closure
fix and clean up benchmark suite