[Evolution] Text selection excludes signature

[Patrick O'Callaghan <poc usb ve>]

Arising from a recent thread, it appears that Evo's behaviour when
using a text selection as quoted material in a reply is not always what
most users would expect. It's probably a rare situation, but if the
selection includes a signature delimiter ('-- \n') the quoted material
will be incomplete.

I've filed a bug report: 

https://gitlab.gnome.org/GNOME/evolution/issues/82

Note that simply replying (with no text selection) should still exclude
anything after the delimiter, which is standard behaviour.

poc