[Pre-release] v0.5.0-6

This is the third release candidate for Thunder v0.5.0! As mentioned in the previous release candidate, there aren't too many notable changes in this version as I'm preparing for a general release version. If no major issues are found, this will be the version released on the App Store and Google Play.

Be fully prepared to know that these pre-release versions may contain major bugs which could cause Thunder to crash or behave unexpectedly.

Fixes

• Fix image proxy thumbnails not retrieving image dimensions properly by hjiangsu
• Potentially fix for markdown toolbar not showing above system keyboard by hjiangsu