Fix typos found with codespell

Fix a lot of typos found and reworked with codespell in src/, modules/ and include/.

One of the most important change is the one in the Qt interface code, but some noteworthy locations are also translated strings.

Note: I tried to remove codespell reports that could be valid, like for succesful. I also removed overriden->overridden, though I haven't found source for the correct spelling, since google translate accepts it.