Merge pull request #260 from zwobit/develop

[extension] - update betterform 5.0rc8
Prevent NPE as reported in https://github.com/eXist-db/exist/issues/254
Smaller code improvements
Avoid NPE for corrupted resources on backup, open query dialog, listing and intentional removal of them in java admin client.
Merge pull request #261 from dizzzz/community_support

Improve SQL extension
Bugfix: BCC list was not iterated
Reviewed MAIL module code, made improvements (readability)
Continued improvement of the MAIL module: better readable null.empty string checks, probably better to use the isBlank() method.
made a manual mistake....
Merge pull request #263 from ljo/develop

Avoid NPE for corrupted resources on backup, open query dialog, listing ...
[bugfix] Allow some potentially long-running index scans in structural index to abort immediately if requested to do so (e.g. during shutdown).
Merge branch 'develop' of github.com:wolfgangmm/exist into develop
Merge pull request #265 from dizzzz/cherry-pick

MAIL module improvements
Merge pull request #266 from wolfgangmm/develop

Allow long-running index scans to be aborted
[bugfix] New range index: start parameter was ignored in implementation of range:index-keys-for-field function.
Merge pull request #267 from wolfgangmm/develop

[bugfix] New range index: start parameter was ignored in implementation ...
Update json.xq

Add a function for simplifying annotating existing XML with json:literal="true" before converting to JSON.
Add startup timeout for wrapper ; gives eXist-db more time to get really started
[bugfix] Check for free disk space in BrokerPool should respect configuration parameter, so one can disable it if necessary.
Merge pull request #268 from dizzzz/service-wrapper-update

Add startup timeout for wrapper.