Make .gitignore and lib/.gitignore more consistent.

Make .gitignore and lib/.gitignore more consistent.

Move the ignore of lib/App/, lib/mro.pm, lib/TAP/, lib/Test/Harness.pm,
lib/File/DosGlob.pm, lib/inc/, Win32.pm, Win32API/ and Win32Core.pm from
.gitignore to lib/.gitignore, where they more logically belong.
Consistently use trailing / for ignored directories.
Add a leading / to the ignore of unicore/TestProp.pl
(The line was added by commit 3df51b85ce4a5664 in Nov 2009, and it's not
clear why it did not have a leading / from the start.)

Re-sort lib/.gitignore lexically.