replace touchSubmatrix() & co with copy()

full code now works without GSL (even ho)

- don't play tricks in Extend1DMesh & co: always follow the option (so we
  can predictbly mix point/curvature lcs with fields)

- removed every "throw;", i.e., every throw that did not throw an actual exception.
  throw wihout args should ONLY be used in a catch{} to re-throw the same exception
  (for it to be handled in another catch clause)

- introduced GmshMessage callback class so that clients can easily implement
  their own message handling (see example in driverOCC.cpp)

untabify

fix gcc warnings

"pure windows" version (without cygwin) is almost there: the solver
interface now works quite nicely using native Windodiows sockets and
the timers work too. There are still some bugs with binary files and
user-created functions in the parser.

New high order interpolation.

JFR