Updated tex/latex

  * isuth-modules/gp-macros.dcf: removed old commands (files used them
    have to be updated), moved code for 'Greek letters swapping' into
    separate package
  * misc/swap-greeks.sty: here.
  * isuth-modules/{asymptote,note,olympiad,org}.dcf: added
    '\usepackage{swap-greeks}' before call '\SwapSomeGreeks'.

Signed-off-by: Vladimir Lomov <lomov.vl@gmail.com>