Use insertPlainText() for Copy/Paste

[thedirk]

Issue: Copy / Paste copies fonts & styles — this causes a fatal error when trying to re-segment, and can mess up the color of list highlighting...

Expected behavior: Paste copies only the "plain text" of the original, and puts it in the format of the Editor

[thedirk]

un-spacing converts old plain text into the new, pasted format!

top: plain text, as entered in the editor itself below: copy/paste brings a new font and new color into the mix

after copying & pasting colored text with a different font, trying to re-segment (scissors icon) creates a fatal error

[kevinhuangtw]

Now the editor will accept plain text (discard format) when pasting sentences.