RICHED20: implement EM_GETFIRSTVISIBLELINE and EM_POSFROMCHAR (3rd try)

[Krzysztof Foltman]

ChangeLog:
 * Fixed a bug in ME_RunOfsFromCharOfs (it didn't take
bEmulateVersion10, I'm
sure we need to handle that differently after a major release)
 * Fixed this bug (the bug was secondary to the first bug)
 * Fixed Steam regression (by ending RTF parsing when the final } was
encountered)
 * Moved some TRACEs to a different debug channel (so that TRACE has now
some actual use :) )

-- 
Krzysztof