Update PLCrashReporter

Includes two more fixes post PLCR RC5 release: https://opensource.plausible.coop/bugs/browse/PLCR-542 and https://opensource.plausible.coop/bugs/browse/PLCR-539
3.5.5 release and documentation updates
Merge branch 'release/3.5.5' into develop
Update CocoaSpec with a fix for some rare integration issues
Remove x flag from BITAttributedLabel.
Remove +x from LICENSE.
Merge pull request #101 from tewha/flags

Flags