Added a strfunction to the various tex builders. Since the sub-actions report

Added a strfunction to the various tex builders. Since the sub-actions report
their commands as they build the strfunction only returns a string for
GetOption("no_exec") which covers --dry-run.
Therefore --dry-run now gets output, the first command to be run plus " ..."
to indicate that the ral builder may repeat or run bibtex, makeindex,...

Also updating the flags to pass -interaction=nonstopmode
This prevents errors in the .tex files from stopping the build
while Latex asks for input.

Updated several tests to handle this new flag by switching to getopt module

git-svn-id: http://scons.tigris.org/svn/scons/trunk@3338 fdb21ef1-2011-0410-befe-b5e4ea1792b1