Background:
The usage and maintaining of SpannableBuilder is reduced by using
a good-old-SpannableStringBuilder directly but making sure its spans are
reversed.
The implementation is credited Uncodin/bypass
* Added retention annotation for Alignment IntDef (#3)
* Task lists (#4)
* Added since annotation to newly added method/classes
* Fixed the indexes bug for margin spans (#6)
* Feature: Revert spans order (#11)
* SpannableBuilder
* Removed nullablity from Markwon class (no null markdown)
* Image sizes via HTML (#13)