Add support for specifying the target location of preloaded or embedded files on the virtual filesystem via --preload-file 'src@dst' notation.
Fix browser.test_preload_file absolute paths on windows. The test would create a string "c:\path\file.txt", where clang would regard path separators as escape characters.
Add warning message print to file_packager to warn user when he accidentally specifies --preload-file to an absolute path, as discussed in #486.
Add browser unit tests to guarantee new src@dst file system packaging syntax feature.
Fix handling of crunched files broken in previous commit.
Merge branch 'fs_destination' of github.com:juj/emscripten into incoming