Add README.md and CONTRIBUTING.md, refs #17189
Add back submodule for less v1.3.3.

This is needed to get dijit/themes/claro/compile.js and dojox/trunk/mobile/themes/utils/compile.sh
working again.  Might be possible to install less via "npm install" instead but this is the path of
least resistance.  Less submodule was originally part of 8525a1a318033ea75bef49c54c1e91688aad49e9.
Update build release script for Git. Refs #17176.
add multiprocess support to uglify optimizer

specify maxOptimizationProcesses in a build profile:
  0 or other falsy value disables multiprocess
  positive number would use that number of processes
  negative number would start one process for each CPU core
    (default is -1)
write string cache entries before module definition when interning strings as required by some IE loader paths; fixes 17146