0.6.5

• Add alternative, compacting gc, enabled with new moc flag --compacting-gc.
  The compacting gc supports larger heap sizes than the default, 2-space copying collector.

  NOTE: Dfx 0.7.6 adds optional field "args" to dfx.json files,
  so Motoko canisters can specify moc command-line arguments. E.g.,

  ...
     "type" : "motoko"
     ...
     "args" : "--compacting-gc"
  ...

• Documentation fixes.

• Command line tools: --help option provides better documentation of command line
  options that have arguments.

• Fix issue #2319 (crash on import of Candid class).