Merge pull request #481 from chungy/master

Add Steam IWAD path for Strife: Veteran Edition
Upstream fix from SVE: Missing break statement

This caused Rowan to fail to take Beldin's ring from you, if and only if
you had full bullet ammo. Transcription error from the disassembly.
Upstream fix from SVE: MF_MVIS flag

The MVIS flag, if set on an object *without* MF_SHADOW, imparts total
invisibility. This is the intended effect on players using double Shadow
Armors.
strife: Fix the name of MAP29, should be "Entity's Lair"

Double-checked with strife1.exe