JS: revert the reversal of <,<=, fixes tdewolff#462

Update readme

JS: parse comma-operator expressions as a list not a tree, fixes tdew…

…olff#451

JS: use average character frequency of sample of JS files for variabl…

…e renaming, reduces GZIP size

cmd: Fix bug for stdin

Add --sequential option to run jobs in serial

JS: fix for declarations in while statements

JS: fix bug for moving var decls and var renaming; const statement mu…

…st have initializer; variable uses in for statement now don't interfere with declarations in for block

Update tdewolff/parse to v2.5.21

JS: fix grouped statement ending parenthesis for objects, fixes tdewo…

…lff#429