pebuild: don't print a newline before each selected phase
news: note additions of stable_masked_use and stable_forced_use subcmds
drop extra variable usage when eval-ing defined functions

Also simplify function sourcing failure messages for banned and
deprecated EAPI functions.
indentation consistency
minor tweaks for failure messages using ${T}
minor variable name and scope changes
__get_func_code: don't echo a newline when a function isn't defined