more variable naming consistency
simplify use()

Drops unnecessary local var usage and simplifies negation logic.
usev: drop '!' use flag prefix if it exists

Matches pms expectations that the flag name should be echoed and the
negation character is not part of the flag name.
give the package.provided virtual repo a 'provided' repo_id

This fixes the error where the portage verbose formatter wants to show
a repo_id for pkgs but none exists for provided pkgs.
pinspect: wrap default variable output in quotes

This way they can be eval-ed or similar in an easier fashion.
pinspect: add unmasks, bashrcs, keywords, and accept_keywords profiles subcmds

In addition, drop implemented commands from todo list.
lint: clean up indentation and whitespace in profiles
textwrap.dedent namespace import consistency
ignore 2to3 cache files
doc: add news symlink
pquery: remove vdbs usage

We just use the vdbs from domain.
pquery: remove --vdb option (use --repo vdb)

Trying to simplify redundant options.