This fixes an unreported bug that prevent imports of
private keys with wrong/unknown extension.
The old logic relied on the file extension, that is
not only weak but plain wrong because the same extension
can have different encodings.
The new implementation is 100% robust because completely
ignores the file extentions and try to load the key with
all supported encodings and algorithms before giving up.
spell check will be done automatically in words by default (when some conditions are fulfilled)
possibility to avoid in words checking by adding :* at the end in spelling.dat
one can add #spellok at the end of a line of code to skip spell check on this line
Rationale:
- there was a lot of large objects passed by value, so potentially
there's a speed bump from this
- even for implicitly shared classes like QString/QList there's still
a (small) cost for copying the objects when there's no reason to
- it's the right thing to do!
