Currently, these variables hold the info about the composing
word, or maybe some outdated info, and it's not very clear
which it is. LatinIME is maintaining the freshness info in
a separate boolean, and uses it throughout the code for many,
many things, leading to much confusion.
The idea in grouping this info is, it can be saved in another
instance and restored later. It can be tested against to know
whether there is actually outdated but kept info or not, and
it should allow to straighten out what is actually currently
being typed. Ultimately, it will eliminate the need for
LatinIME to keep track of the status of the info in the
word composer.

Change-Id: I00e2c690f303f8320c9be35590a6df4583e9e456