Allow for plugins to get the current path

[mchelem]

Currently, there is no way for url plugins to get the current path. This information may be useful to compose a file url.

For example, I developed a terminator plugin (urlplugin) that allows me to click on the results I get from grep and open them using vim or gedit (see demo here: https://github.com/mchelem/terminator-grep-plugin/wiki).

In order to be able to open the files, I must get the current path and this information is not available, so I added it (in the most obvious way):
I put the current path as a field in urlplugin: urlplugin.current_path = self.get_cwd() (see attached diff). I didn't just pass the current path as a parameter because this would change the callback interface and potentially break other url plugins.

Not sure what is the best design here, but I am eager to implement once I get one word or two from more experienced folks.