Use php functions instead of imap functions

[bramley]

Description

The php-imap2 package used by the IMAP2 plugin doesn't replace the imap_qprint and imap_base64 functions correctly. To avoid any problems with using those functions the equivalent php functions quoted_printable_decode and base64_decode can be used instead.

Related Issue

#1063

Screenshots (if appropriate):

[michield]

sorry, there's an annoying conflict due to me editing the /PULL_REQUEST_TEMPLATE.md

I've set the target branch to the release-1.7.0

If you update the conflict we can mark this ready to merge.

[bramley]

I have rebased my changes onto the release-3.7.0 branch locally and force-pushed my change. That seems to have removed the conflict with PULL_REQUEST_TEMPLATE.