[Bug #1545726] Incorrect FSF address in many extension files.

Second round of extension executable bit cleanup. Add/remove executable bits and shebangs as appropriate. The extension entry point should be executable, while Python files that contain libraries and are not entry points should not be executable. Shebang lines should only be present in executable files.

extensions. ink2canvas.py. pass reference to self (Bug 1258473)

Adding extension submitted by Karlisson (launchpad id: karlisson) that converts an SVG document into an HTML page using canvas commands to render the given graphics. This is Karlisson's second accepted contribution to Inkscape (he is also the author of the text split extension). This means he now can get commit access to our development repository.