Merge pull request #64 from lewtds/refactor
Implement basic charset conversion infrastructure.
Change the way to generate encoding_map
Integrate charset conversion into ibus_engine.
Modularize/generalize charmap-based codecs.
Clear some confusion between MemoryView and bytes in codecs

When we use bytes.decode() then `input` will be a `bytes` but
when we use file.open(path, encoding='tcvn3') then `input` is
a `MemoryView`.
Add tests for charset converter
Integrate vncharsets into the GUI tool
Add test data for charset converter. Fix travis build https://travis-ci.org/BoGoEngine/ibus-bogo-python/builds/5708620
Merge pull request #68 from lewtds/charsets

Charset converter