Compiling errors fixed in this commit:
* Various cases of mixed declaration and statement code
* Implicit declaration of slope functions (read: you forgot to put "include "p_slopes.h" in MORE than a few places)
* an odd case of a bad fixed_t to float typecase, cause by using P_GetZAt directly inside FIXED_TO_FLOAT
* a few minor cases of bad unsigned-signed comparisons
* no prototypes for some of the new slope functions. For goodness sake Red, this is basic stuff!
These functions were already here before, and I /swear/ the slope
physics became slightly less glitchy after switching to them...
Only issue is the slope plane mapping code hasn't been properly
converted yet, so they don't render properly for now.
