Realign summaries view in help
Omit helptext if it's only space/tabs/new lines
Enable the %COMMAND% placeholder in help text too
Export additional info as environment vars

- All subs now get the full path to the running command in the
  _%SUB%_COMMAND_PATH variable.
- SH type subs get a variable called _%SUB%_IS_EVAL set to 1.

In both cases, %SUB% is the name of the sub in capitals