Add resourceUriTargetCache to SMW\SPARQLStore\RedirectLookup

XDebug profiling uncovered that repeated requests are made to the same
resource uri and to improve performance an in-memory cache is added to
avoid unnecessary DB lookup requests for already known uri's.
Add dataItemExportCache to SMW\SPARQLStore\TurtleTriplesBuilder

Improves performance especially when subobjects are involved.
Localisation updates from https://translatewiki.net.

Change-Id: I0b045c3577422fa4a0eb0e9b65f3003dfe02eef4
Update SMW_LanguageZh_tw.php

Translation update kindly provided by [Linforest](https://semantic-mediawiki.org/wiki/User:Linforest)
Merge branch 'master' of ssh://wmfgerrit/mediawiki/extensions/SemanticMediaWiki
Localisation updates from https://translatewiki.net.

Change-Id: I7fbf708b4943c42f7f767de07bfade82a52615f3
Update en.json

Add missing system message (see issue https://github.com/SemanticMediaWiki/SemanticMediaWiki/issues/181)
Update qqq.json

Add system message description (See issue https://github.com/SemanticMediaWiki/SemanticMediaWiki/issues/181)
Merge pull request #505 from s7eph4n/master

Fix highlighting of results
Merge pull request #503 from SemanticMediaWiki/i18n-zh-tw

Update SMW_LanguageZh_tw.php
Merge pull request #487 from SemanticMediaWiki/sparql-redirectlookup-cache

Add resourceUriTargetCache to SMW\SPARQLStore\RedirectLookup
Update RELEASE-NOTES.md

[skip ci]
Merge pull request #506 from SemanticMediaWiki/i18n-188

I18n 181
Update en.json

Add gender support as per [translator request](https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Smw_smwadmin_datarefreshstopconfirm/es)
Update qqq.json

Add gender support as per [translator request](https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Smw_smwadmin_datarefreshstopconfirm/es)
Merge pull request #509 from SemanticMediaWiki/i18n-58631

I18n 58631
Localisation updates from https://translatewiki.net.

Change-Id: I48fbad6d024f4dac3e3f0cea3564cfcafb304e19
Merge "Localisation updates from https://translatewiki.net."
Merge branch 'master' of ssh://wmfgerrit/mediawiki/extensions/SemanticMediaWiki
Add Benchmark tests

Benchmarks tests are using PHPUnit.

- JobQueueBenchmarkTest
- QueryEngineBenchmarkTest
- RebuildDataBenchmarkTest

Group `semantic-mediawiki-benchmark` is generally excluded from unit
testing but doing
`php mw-phpunit-runner.php --group semantic-mediawiki-benchmark` will allow
to run benchmarks individually that are assigned to the
`semantic-mediawiki-benchmark` group.