MOD_TraceLine now behaves the same as id's SV_RecursiveHullCheck (from
WinQuake). This means that even if the trace would escape from solid space
into non-solid space, the trace is treated as allsolid if it crosses from
one solid space to another before hitting the empty space.
trace-id.c is used only for establishing the behaviour of id's code.
We need to figure out a way to make docs in unusual places, like in the
SourceForge shell environment -- which doesn't have an extremely recent
autotools. This is an extremely stripped-down automake/autoconf setup that
provides the bare minimum needed to AC_SUBST variables.
It's dirty and hacky, but it kinda works.
