Q3Map2/VIS

VIS phase minor switches

 * -fast : Only calculates rough visibility data. Quick and dirty, not actually useful for VIS purposes.
 * -hint : Will merge the bsp leaves (except for hint portals) before calculating the visibility list.
 * -merge : Will merge the bsp leaves before calculating the visibility list.
 * -nopassage : Disables the passage visibility algorithm. Passage VIS is a bit faster and tighter than the old algorithm.
 * -nosort : Disables the sorting of portals by complexity. Sorting speeds up visibility calculations.
 * -passageOnly : Will use the passage visibility algorithm only.
 * -saveprt : Disables the automatic deletion of the .prt portal file after VIS finishes.
 * -v : Enables verbose mode. Always use this.