Gwenhywfar

Fix minor complaint of cppcheck of missing va_end, but this is an error condition anyway.

Fix compiler warnings about unused variables.

GWENTEST: Added tests for passive SyncIOs.

HTTPSESSION: Added function GWEN_HttpSession_fromSyncIoPassive()

- needed to start a HTTP session from a prepared SynIO object

OS: Added debug messages.

OS: Added some remarks.

BUILD: Incremented build number.

Reverted a number of patches which were directed towards improving the
readability of msgengine.c.

However, that beast is hard to tame... The latest changes introduced new
problems so they had to be reverted.

Revert "MsgEngine: Started improving readability."

This reverts commit 74be35ab054e707fbdc8332613f108773c4f72b9.

Revert "MsgEngine: Further improved readabilty."

This reverts commit 3ae5e69990845c6edf69502b3d661ac6903b639c.

Revert "MsgEngine: More work on improving maintainability."

This reverts commit 6c2f9046916ed0efcc6b40c07e6bd2b916959769.

Revert "MsgEngine: Started refactoring of msgengine."

This reverts commit 7db0eea44f5ce73bbb2a1832cb855713cafba610.

Fix compiler error with mingw-x86_64: "long int" is still 32bit there.

Hence, the 32 bit "long int" must be cast to a 64bit int first, then
to a pointer. Explained here nicely:
https://stackoverflow.com/questions/384502/what-is-the-bit-size-of-long-on-64-bit-windows?noredirect=1&lq=1...

Fix detection of <libintl.h> for windows cross-compile environment.

It is not available in a plain Ubuntu 18.04 mingw-w64 cross-compile
package, so configure must correctly detect that it is not there.
It is available in the gnucash jhbuild env, though. This should...

Provide visibility to Qt5 dialog code

Make the Qt5 dialog code available so that it can be sub-classed.

Simplify gnutls lookup: pkg-config is fine for windows, too.

Also, as gnutls>=2.9.8 is required, the check for the function
that exists since >=1.6 is no longer needed.

MsgEngine: Started refactoring of msgengine.

BUILD: Include -Wunused-parameter.

MsgEngine: More work on improving maintainability.

MsgEngine: Further improved readabilty.

MsgEngine: Started improving readability.

- split msgengine.c into multiple files
- split spaghetti code functions into smaller parts

Update German translation

Result of "make merge".

SAR: Disabled warnings.

Result of "make format".

Fixed typemaker2 targets.

Having these targets sometimes leads to "make" thinking that files have
to be rebuilt by typemaker2.