xorshift* PRNG
This needs testing to ensure I didn't mess anything up switching function names around.
Our PRNG sucks. This is probably obvious. I wish I had known better at the time I implemented it, but oh well.
The replacement is an xorshift* PRNG variant with period 2^32 - 1 (meaning that the PRNG state will loop after four billion calls ... that's not likely to happen), versus the old PRNG's period of about 2^22 (?). The output is also much more random and less predictable; the old PRNG would fall into a predictable loop of output after about 4000 numbers were generated, which isn't much.
The PRNG here also outputs numbers as fixed point from [0,1) (that's 0 to FRACUNIT-1, in other words) instead of single bytes at a time. This makes it much easier to calculate things for, say, P_RandomRange and P_RandomKey. A new macro, P_RandomChance(p), is now in use that returns true _p_ percent of the time, where _p_ is a fixed_t probability from 0 (0%) to FRACUNIT (100%).
This doesn't affect netgames at all; the code for seed saving and restoring is identical (aside from a check to prevent seed being set to 0, which breaks xorshift PRNGs). Demos break, but A: _duh_ and B: they're already broken by all the changes to physics to accommodate slopes.
P_Random is deprecated in Lua, as the function was renamed to P_RandomByte. Aside from that, nothing special.
See merge request !64
Skybox hotfix
This branch fixes how, for a skybox with both a centerpoint and viewpoint, the first person view code did not take the centerpoint's angle into account. So when the centerpoint's angle is NOT 0 (or a multiple of 360), this results in the skybox "moving the wrong way" when you're viewing the skybox this way and moving about.
...yeah sorry guys, I commited to a copy of next again, whoops. Cherry-pick the relevant commit into master if this works out fine - after all, this shouldn't affect netgames I think (it's purely about rendering after all)
See merge request !56
* add skidtime, which we forgot before 2.1 release apparently
* change tics from INT16 to INT32
* change eflags from UINT8 to UINT16
* change actionspd/mindash/maxdash from INT32 to fixed_t
Until we use something besides Native MIDI to play
back MIDI music, MIDI volume changing is disabled
since it causes way too much of a damn headache.
(It's not even our fault, it's fucking MS.)
