SVN handles and Git names are merged into one person.
return early with 0 from cansee() if either sector is >= MAXSECTORS.
Previously, only the <0 condition was checked. However, the passed sectnums could be >= MAXSECTORS (at least in C-CON), for example when issuing 'canseespr' on a sprite not in the game world.
make neartag accept a sprite-blacklist function and use it in sector.c.
Internally, the last argument to neartag is now a pointer to a function int32_t (*blacklist_sprite_func)(int32_t i), which is supposed to return 1 if sprite[i] should NOT be considered for hitting. This is now used in the hard-coded neartag() calls in sector.c, but not in any way in CON (there's neither a C blacklist function provided, nor is there a possibility to define one in CON). There, all sprites with picnums >=1 and <=10 (i.e. the effectors) will be blacklisted. This remedies problems where such sprites would get in the way of switches. Note that a whitelist approach (only consider a predefined set, namely those picnums which will be checked afterwards) has back-compatibility implications since people may have used e.g. lotagged window sprites to cover a switch. Also, the >=1 to <=10 range is [sic] (the static, not dynamic values are used), since anyone redefining effector picnums is clearly out of their mind.
