q3df compat: add support for target_fragsFilter spawnflags

This adds support for the spawnflags used by target_fragsFilter, there are 4 spawnflags of which one is unused even in q3df. The 3 implemented spawnflags are:

• remover: consumes the frags that were needed to trigger it
• silent: hides the "x more frags needed" message (the message was also added in this branch, it was previously not present)
• reset: resets the frags to zero.

One map which makes use of them is r7-blockworld1 where you can buy weapons and boosts, the currency being scripted with target_fragsFilter.