Add patch functionality

[feruzm]

Hello Adam,

I wonder, if it is possible to use

patches = dmp.patch_make(text1, text2)
patch = dmp.patch_toText(patches)

with your library?

[amweiss]

I don't currently have any of the patch functionality implemented as I didn't have a use for it at the time. The format of it is slightly different than the standard command line tools but it shouldn't be too hard to do.