Merged from trunk 6185:6199

Merged from trunk 6185:6199

For bug #169620, in --tree display always show the dowload size on the
node that is "ordered" rather than one of it's "nomerge" counterparts.

Fix 2 more types.InstanceType comparisons that are broken by the
transition of dbapi to new-style classes.

Take marien's advice, turn Skips into Todos for clarity sake

Part of my attempt now involves cleaning up config; this means for me;
removing the file-based stuff from it (config_path) and encapsulating
that into classes.  This is the first one, a simple PackageKeywords
class that does file-based stuff, no recursion yet but soon. Trying to
do TDD here as well,so tests first then code.

Change load() to have no default arguments, makes caller specifiy
explicitly...I think assuming a default arg is bad here.  Also add
PackageUse and PackageUseFile, change up the comments a bit.  I've
started to notice code re-use here; these are basically the same
code.  I think I will write up the rest of the package* classes and
then perform code merges to save LOC and memory and whatnot

add PackageMask{File} classes, change unit tests to use try/finally,
makes sure the tempfile gets destroyed even if something weird
happens

whoopse, s/;/:/ (WarnerBro)

Remove legacy "masked by: profile" support as per bug #149508.
Profiles should use package.mask to mask unwanted versions of system
packages.

Use the full atoms from the system set, since profile masking does
not automatically constrain the matches anymore.

Remove the "masked by: profile" support from getmaskingstatus().

Remove profile masking of system packages from the docs.

Display message about --buildpkgonly restriction in pretend mode as
well

svn path=/main/branches/prefix/; revision=6200