Report debug diagnostics in file packager if EMCC_DEBUG=1. Make file packager skip all path components that have a path starting with '.', like ('.git/xxx/yyy/'), or the filename starts with '.', or the file is a Win32 hidden file. Explicitly specified files on the command line are always packaged, even if they start with '.' or are hidden. Add unit tests to check that it works.
Rename emcc_debug to DEBUG in tools/file_packager.py to be consistent.
Merge pull request #1288 from juj/dont_package_hidden_files

Report debug diagnostics in file packager if EMCC_DEBUG=1. Make file pac...