On using HTML tags, HTML formatting is being applied instead of plain text

[nuttyartist]

As @bjorn reported in #293, when using HTML tags, the textEdit applies its formatting to the text, when it should rather stay plain text. As he writes:

I did notice that stuff like <b>foo</b> can turn into bold text when re-selecting the note.

@bjorn suggestion of using setPlainText instead of setText on the QTextEdit solves this issue.