Scan for IWADs in "/usr/share/doom" as well, by request.

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2593 86ba831e-150c-0410-ab35-e06eaae15ed9
* Lockdefs support in EDF (not entirely complete)
* Small tweak in d_main

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2594 86ba831e-150c-0410-ab35-e06eaae15ed9
Use $XDG_CONFIG_HOME before ~/.config when searching for user dir in home.

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2595 86ba831e-150c-0410-ab35-e06eaae15ed9
* Define DOOM lockdefs (with some allowances for ZDoom compat)
* Integrate lockdef processing

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2596 86ba831e-150c-0410-ab35-e06eaae15ed9