Use latin1 encoding most of the time where default encoding was used
before. Qt 4 assumes latin1 by default while Qt 5 uses utf-8 which is
not what we want.
Use utf-8 encoding in some places where default encoding was used before.
This includes strings coming from RPC.
Fix an issue with SortMode::names[] (filters.cc) where missing comma
between "sort-by-queue" and "sort-by-ratio" resulted in two array entries
being merged into solid "sort-by-queuesort-by-ratio" string and all the
following items being shifted compared to their enum counterparts.
1. add the option the code to be used under GPLv2 or GPLv3; previously only GPLv2 was allowed
2. add the "proxy option" as described in GPLv3 so we can add future licenses without having to bulk-edit everything again :)
3. remove the awkward "exception for MIT code in Mac client" clause; it was unnecessary and confusing.