EMailAccountManager: Rename "Restore Default" button.

Rename it to "Reset Order".  A little less confusing, I think,
since there's also a "Default" button to set the default account.
Alarm-Notify: Skip disabled sources/calendars

Trying to open sources which are disabled violates user's will,
thus do not do that.
Updated Polish translation
Bug #711835 - Clang build in broken: void function 'cal_comp_transfer_item_to' should not return a value
Generate documentation for libemail-engine.
Rename e-mail-enums.h to e-mail-engine-enums.h.
Fix misspelled enum type.
Remove unused EMailDisplayStyle enum.
Generate enum GTypes for libevolution-mail.

Steals some enum types that libemail-engine doesn't need to know about.
Move EMailImageLoadingPolicy to e-mail-formatter-enums.h.

libemail-engine doesn't need to know about this enum.
Convert libemail-engine to a single-include model.

Use: #include <libemail-engine/libemail-engine.h>
Fix some cppcheck warnings (uninitialized variable usages)
Updated Malayalam Translation
Update Dutch translation Master
"Disco is dead!", says Camel.

All offline-capable Camel providers use CamelOfflineStore now.
EMailBackend: Camel no longer has a "network-available" property.
Fix/mute issues found by Coverity scan

This makes the code free of Coverity scan issues.
It is sometimes quite pedantic and expects/suggests some
coding habits, thus certain changes may look weird, but for a good
thing, I hope. The code is also tagged with Coverity scan
suppressions, to keep the code as is and hide the warning too.
Also note that Coverity treats g_return_if_fail(), g_assert() and
similar macros as unreliable, and it's true these can be disabled
during the compile time, thus it brings in other set of 'weird'
changes.
Updated Greek translation
Updated POTFILES.in
Updated Spanish translation