Miscellaneous memory bug fixes to make AddressSanitizer happy

Fixes a whole series of memory bugs – in netcode, dehacked, input handling and hardware rendering – most notable of them all being I_NetRequestHolePunch not taking a node parameter, instead relying on doomcom->remotenode even though its only calling function itself takes a node parameter that specifies what I_NetRequestHolePunch would expect in doomcom->remotenode, and does not set the latter, resulting in an address being taken from index -1.

Combined with !309 (merged) and !295 (merged) (which removes an ill-advised strstr), this branch allows SRB2Kart to happily run under AddressSanitizer, except for some further bugs (including one triggered by spectating mid-race) that !309 (merged) will have a fix for… once I find one.