Encode big parts in quoted-printable

We now encode messages in quoted-printable when content is bigger than
72 bytes.
Disabled encoding to broken entities.
Fix for bug #2549
Fix for bug #2550
Fix for bug #2551
Fix for bug #2553
Fix for bug #2554
Fix for bug #2566
Silented massively annoying log messages.
Fixed include for old gcc versions
Raise exception when not enough memory available