initial work to support python rules

this is done using the boost::python library.

A simple rule to check there is no space at the end of the lines would look like:

  # no trailing space
  for f in vera.getSourceFileNames():
    for lineNumber, line in enumerate(vera.getAllLines(f)):
      if line.endswith(" "):
        vera.report(f, lineNumber+1, "trailing whitespace")
merge master
Merge branch 'master' into python
Merge branch 'master' into python
Merge branch 'master' into python
python scripts are now usable

getTokens can now take a python list of string as parameter
add a few python tests, but keep the python rule in the test dir to avoid
duplicating the rules
allow to pass the rule with the extension .tcl or .py to force the execution
of a rule with a specific language
Merge branch 'python'