General code cleanup, whitespace, dead code removal, added missing prototypes.
Made Xquartz come to foreground later in startup, so it doesn't appear for Xquartz -version
(cherry picked from commit 36922e8ff4316c93843aa3fe959cf8df3c7d5892)
Leaving xpr unflattened since we want modularity to replace that with xpc (XPluginComposite) at some point
(cherry picked from commit 48e6a75fbdd0fee86e364f02ace83f20b312a2b2)
Jeremy Huddleston