Mms: Delay unicode stripping from a message

Using an InputFilter for stripping has some unwanted
consequences. First of all it totally messes up dictionaries
for suggestions. Usually user taking advantage of unicode
stripping wants to text without non-GSM chars, but wants
to have full and correctly spelled suggestions in other apps
(e.g. email). The InputFilter approach results in having stripped
suggestions everywhere.

With this change the app strips unicode characters only for the
purpose of counting available characters counting and to convert
the text right before sending the message. This way the user
can compose messages (and have his drafts stored) with all
characters and can see his stripped messages in the conversation
history after (to be aware that it has been stripped
of unicode chars).

This makes the app behavior consistent with many popular apps
(e.g. GO SMS, Handcent) meeting users' expectations.

Patch set 2: fixed initialization order in QuickMessagePopup.java
Patch set 3: rename class: StripUnicode -> UnicodeFilter

Change-Id: I44ac859d286958d036ddd67a6820a4c09a393644