More Heretic DECORATE state conversion

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2628 86ba831e-150c-0410-ab35-e06eaae15ed9
* Some more Heretic conversion work
* XLParser shall add all lumps it touches to the EDF data source hive, so that lumps are never processed more than once.
* SNDINFO processing shall occur in E_ProcessSounds, *before* EDF sound processing, so that EDF naturally overrides SNDINFO without need for a hacky $edfoverride keyword in the latter. Apologies to ZDoom crew, as they should now remove that keyword. EE will ignore it at this point.

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2629 86ba831e-150c-0410-ab35-e06eaae15ed9
* Fix a followcam bug that was leaving followcam.groupid 0
* Use lambda function to sort vertices for followcam

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2630 86ba831e-150c-0410-ab35-e06eaae15ed9
Additional minor C++11 tweaks and cleanup in p_chase.cpp

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2631 86ba831e-150c-0410-ab35-e06eaae15ed9