Remove normalization functionality from router

Because the router does not have full context of where text is coming
from (e.g. note field, on-the-fly text, user input), it really doesn't
have all the wherewithal to figure out the best way to normalize it.

This becomes more problematic when we start dealing with how to treat
cloze and parenthetical text in a sane manner. With this branch, it will
become the responsibility of the caller to the router to figure out how
to do normalizations of the text.
Replace STRIP_ALL with more nuanced stripping

This adds new stripping options in the 'addon' bundle to include
strip.from_note (for BrowserGenerator runs, future prepopulation of
modals from note fields), strip.from_template (for on-the-fly),
strip.from_user (for direct user input in previews or EditorGenerator
insertion), and strip.sounds (to continue to allow stripping of sounds
where necessary, e.g. the BrowserGenerator's removal of old sounds or
the Reviewer's handling of faking the {{FrontSide}} placeholder that
Anki uses).
Add normalizations before router calls

Updates all GUI components to correctly normalize input text before
calling the router, given their context.
Simplify router __call__ initial debug statement

Since text is no longer actually normalized within the router, this no
longer really needs to regurgitate the input text twice.
Reviewer regression with "empty" text

The reviewer (i.e. on-the-fly mode) is supposed to silently ignore empty
tags, but the stripping was placed in the wrong place causes a
regression in that guarantee.

This fixes that by moving the text stripping to be immediately above the
'if not text' check that does the 'continue' to ignore the tag.
Merge branch 'chg/text-normalization' into develop

Brings in changes for where in the code text normalization happens and
how specifically that can be tailored given the context.

In sum, this allows text input from a note field to be treated
differently from text input from the user or text input from on-the-fly
mode, laying some foundation for issue #15 and issue #22.