Revert "IMAP: defer bailout in case of EOF"

This reverts commit afb1d1949e7bb9849e0fe33e4d3ae971711337bd.
Fixed long (>255) utf8 headers + unit-test
Added validation of invalid utf8 sequences (replacing invalid char with "?") + unit-test
Merge branch 'dbmail_3_1_utf8_fix' of https://github.com/alyarskiy/dbmail into dbmail_3_1
fix unit-tests after merge