Spell checking in FocusWriter

I have added spell checking to the FocusWriter repository, but there are more things I plan on changing before making a release. I decided to use Hunspell as the spell checking engine so that I could use the same engine on all platforms. It turned out that the act of checking the spelling of a word was very easy (the functions spell() and suggest() in Hunspell do the actual work), but the integration was a pain and it took me a lot longer to write than I was expecting. FocusWriter now has “as you type” spell checking and a spell checking dialog.