Fix encoding of mail headers content-type and content-type-encoding
for single-part mime mails.
Fix spacing
Fix spaces
Fix spaces
Fix spacing
Spaces fixed?
Fix identation (again) + return val
Fix eof_ending + identation change in unchanged code
remove package, subpackage and category

as requested by @samsonasik
Fixes problems highlighted by @DASPRiD and @Maks3w
- do simple in_array comparison for transfer encoding
- remove to many spaces befor equal sign
- use camelCase var names
Merge branch 'Maks3w-hotfix/many-mail-issues'

Close #5291
Merge commit 'refs/pull/5140/head' of github.com:zendframework/zf2 into hotfix/5140
[#5140] Adapt changes to actual master changes.

Adapt code to design changes added by #5291 and #5303
Forward port #5140