invalidate the subtype_cache when removing a subtype
ElggSite->getURL() returns the site url instead if view/<guid>
as request by mrclay return a boolean
Fixes #6309: Fixes notify_user() broken by 63db31c
Merge pull request #6311 from mrclay/6309_fix

Fixes #6309: Fixes notify_user() broken by 63db31c
Fixes #6294 : Correct handling of email login
Prepare for 1.8.18 release
Merge pull request #6316 from gerard-kanters/patch-4

Fixes #6294 : Correct handling of email login before validation
Fixes incorrect commit c20c4e3
Merge pull request #6328 from mrclay/fix_6294

Fixes incorrect commit c20c4e3
Test for ElggSite::getUrl
Merge branch 'jeabakker-site-geturl-should-return-siteurl' into 1.8
Test for remove_subtype()
Merge branch 'jeabakker-invalidate-subtype-cache-on-remove' into 1.8
Make ElggCrypto::getRandomBytes static