Gwenhywfar

crypt3: Added convenience function GWEN_MDigest_Digest()

base: Added GWEN_SimplePtrList with test code

- introduce a fast pointer list (needed by AqDatabase) with lazy copying
and copyOnWrite capabilities
- introduce test code accompanying modules (first: simpleptrlist-t.c)

Prepared release 4.99.25rc9

Fix mismatching number of arguments from 497436bd

SIO: More work on server mode http session.

gwentest: Fixed a bunch of compiler warnings.

SIO: More work on passive http session.

SIO: Added function GWEN_HttpSession_SendResponse()

- this function is used in server mode

Fixed gcc warnings.

Rewire gwenhywfar-config to use pkg-config

Replace all functionality behind '--with-gwen-dir' with usage of the PKG_CONFIG_PATH environment variable

• Suggest setting that environment variable when gwenhywfar.pc is not found
• Abort if '--with-gwen-dir' is still used, but print a helpful error message...

Minor tweaks

- refer to git instead of to svn
- use https for the website references

Replace gwhenhywfar-config use with pkg-config

For this the gwenhywfar.pc now needs to expose more variables.

Fix typo that confused Param_Type with Param_DataType in test code.

Fix typo that confused the cryptAlgoId with cryptAlgoMode in CryptAlgo_toDb(), as pointed out by clang.

Update of travis configuration: Use newer Ubuntu 18.04 "bionic" environment instead of 16.04.

Also, run make check, too, but only without network checks.

Fix Clang compiler warning that GWENHYWFAR_API must not appear for struct declaration.

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.