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The API we use hasn't changed from ver. 1, however the config file was
pointing specifically to ver. 1. With this change, the config file isn't
used anymore, instead we dynamically load libenchant according to the
following order: ver2, ver1, "any version" (libenchant.so, as a fallback
method if the other two don't exist).

Fix misc. typos

See merge request !5

Found via `codespell -q 3 -S *.po,./src/External,./NEWS,./src/SubLib/ChangeLog -L uin`

Also fixed some mnemonics which weren't correctly assigned to their
corresponding widgets.

Also cleaned up some tab characters.