Adds support for multi-image attachments.
Also changes individual if-statments in "getAttachments" to if/elseif
as each post can apparently only have one attachment anyway.
* [YouTubeCommunityTabBridge] Improve building of content & title
Fixes truncated link hrefs in content and adds some general
improvements regarding the building of item content and item title
* [YouTubeCommunityTabBridge] Fix PHP deprecation warnings
Fixes the following deprecation warnings:
substr(): Passing null to parameter #1 ($string) of type string is
deprecated
Because "contentText" is always present, PHP warnings were previously
generated for posts without text.
Existence of sub-property "runs" gets checked now to avoid this.
As YouTube doesn't provide precise dates for community posts, an
increasing multiple of 60 seconds is subtracted from each timestamp.
This ensures that the original order is always preserved, even if there
are multiple posts with the same date (e.g. "1 month ago").
