Fix bug #293: GCC 4.8 and the asm_fast grades.

configure.ac:
     Pass -fno-tree-dominator-opts to GCC 4.8 on x86-64 and x86; gcc labels
     are not working correctly in the presence of that optimisation.

NEWS:
     Announce the above.
Fix overlong lines in the usage message.

compiler/options.m:
	As above.

library/type_desc.m:
	Delete a stray '%' in a comment.
Branches: master, 13.05.

Make the calculator example handle CRLF line endings.

samples/calculator.m;
	As above.
Fix non-compiling code in extras.

extras/monte/rnd.m:
	s/index0_det/det_index0/
Fix a problem with the erlang grade on Windows.

m4/mercury.m4:
	Only keep the basename of ERLC and ERL if their initial values
	are qualified with directories whose names contains spaces.  This
	avoids build problems on Windows.  (We do the same thing for the
	Java tools.)
Fix an error in the usage message.

compiler/options.m;
    Delete a duplicated word in the description of the trail grade component.
    Also, mention that the Erlang backend does not support trailing.