integrate new rich text editor

[nebomuk]

https://github.com/wasabeef/richeditor-android

[nebomuk]

can export spanned, but needs to be patched to be compatible with Qt's html rich text capabilities
https://github.com/1gravity/Android-RTEditor

[nebomuk]

https://github.com/NightWhistler/HtmlSpanner

This could replace the existing html parser

[nebomuk]

current candiate for the new rich text editor
https://github.com/chinalwb/Android-Rich-text-Editor