[evolution-patches] patch for Natzilla bug 52476

[Larry Siden <lsiden comcast net>]

The attached patch is meant to be run against the Evolution 1.4.5
release (-r EVOLUTION_1_4_5).  It should be run with -p0 in the top
project folder.  When done, it will allow users to clear the follow-up
tag from a message or messages for which it was previously set.  

I hope it will be merged and released with 1.5 as well, but I am not
currently set up to build and test 1.5.

Thank you,
Larry Siden
http://umich.edu/~lsiden