Since teleporation gives a "you matrialize" message even when
arriving close by, the old behavior of not learning a scroll of
teleportation when you land quite close to your original spot
no longer made sense. Always [almost] discover teleport scroll
when reading it.
Also adds one-shot teleport control when reading a blessed scroll
of teleportation. I changed that to be prevented when hero is
stunned, same as with full-fledged teleport control.
I reworded or reformatted several of the comments. And removed
the EDITLEVEL increment in patchlevel.h; save and bones file
contents are not affected.
I've also added an unrelated comment about reading mechanics to
doread().
Closes#386
81ec2bfa2a