Update netrw to 147d.

This fixes an issue where netrw was clobbering some settings set in
FileType autocommands.
Patch netrw to make it re-setup options set in FileType events.
Merge branch 'js/update-netrw'
Add a Powerline colorscheme that plays better with szakdark.

This basically re-adjusts the colors for inactive windows so the status
line doesn't get lost in the background.
Add SetupVimC() function for Vim-formatted C source.
Merge branch 'js/add-powerline-szakdark'