Instead of indexing `Key` objects that have multiple names by each
individual name, index by the set of names. This reduces the size of the
default key dictionary by a factor of between 2 and 3, and as result
also reduces reallocations/defragmentation.
Instead of instantiating all module/extension keys by default, append
them to the `maybe_key`-generator list.
WinCompose requires the `enter` key to be typed at the end of a special unicode character. In order to help print emojis and emoticons in a windows environment, I have added the enter key to the Windows compose unicode sequence method. I have tested this with my local keyboard.
