Merge branch 'idk-what-to-call-this-branch' into 'next'

A_SetObjectFlags tweak

Only reset the sector/blockmap links on an object calling A_SetObjectFlags if the MF_NOSECTOR|MF_NOBLOCKMAP flags change. Fixes a freeze related to LD442 demonstrated in MascaraSnake's example WAD at https://dl.dropboxusercontent.com/u/27962790/statetest.wad .

See merge request !11