This makes the code free of Coverity scan issues, except of the doc/
folder. 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.

The top-level headers are named after the library:

    #include <libebackend/libebackend.h>
    #include <libebook/libebook.h>
    #include <libecal/libecal.h>
    #include <libedata-book/libedata-book.h>
    #include <libedata-cal/libedata-cal.h>
    #include <libedataserver/libedataserver.h>
    #include <libedataserverui/libedataserverui.h>

Including individual headers will cause a compilation error.

ESource
ESourceExtension
ESourceRegistry