[mms] Horde_Mime::quotedPrintableEncode() is deprecated.
Don't use Horde_Mime::quotedPrintableEncode().

Horde_Mime is no longer a direct dependency of Icalendar
Don't use Horde_Mime::quotedPrintableEncode().
[mms] Improved MIME encoding.

Now tokenizer based (no longer uses regexs and charset conversion).

Fixes tokenzing in some edge/fringe cases, such as data that looks like
a MIME encoding delimiter but isn't.

Should be more efficient also.

Add a bunch of test cases
Fix lazy loading in preview pane
Abstract out lazyload preload percentage so it can be more easily overridden locally