re-implement inplace_change -> formatTemplate

Details:
rather than using the custom '%var%' syntax, use python's built-in
string formatting. The values of the parameters are now passed in as a
dict, simplifying the formatting to one function call.
drop dest when un-necessary (long option specified)
shorten option lines
fail when template is not given

Details:

The default template was an empty string. When not specified, the code
would crash without a meaningful error message. If this is a required
option, then we should check that it's being specified (done
now). Otherwise we should have a default template (doesn't make a lot
of sense to me).
prefer os.remove to getcommandoutput
modified template goes to the directory from which we get the template

Details:

without this change, the modified template is created in the current
directory; by default, pwd is not in pythonpath. The directory where
the script and the template are, however is in pytonpath.  This change
fixes the error

  No module named mytemplate

We might need to change it if we decide to have one dir for templates
and one for actual modules.
prefer __import__ to import

Details:

with this change we avoid having the name of the module defininig the
model hardcoded in the script.  This is motivated by the fact that we
might want to generate several models from the same script
(e.g. varying one parameter).

For more details, see
http://stackoverflow.com/questions/1156356/import-dynamically-created-python-files
allow for output model file on cmd-line
options -> opts (shorter lines, <100char)
add comment and main
avoid % in comments (messing up format)
avoid import *
avoid import pylab *
Merge branch 'clement_build' of github.com:gerbaudo/fbu into clement_build