Cleanup whitespace.
[environment] Permit true/false for boolean command args.
[dylan-compiler] Show banner for command loop, not at CLI by default.

We don't need to show the banner (copyright notice and help text) every
time the compiler is invoked to do a build from the command line. If
someone wants this, they can use -logo=yes.

We should show the banner when entering into the main loop.
Merge pull request #835 from waywardmonkeys/banner-cleanup

Banner cleanup