#195 Automatic format buttons

[Anonymous]

At present, it is possible to format text in entries,
using some LaTeX commands (e.g. \textbf{} for bold) and
some HTML-like commands (e.g. for
superscript). It would be nice if there were a few
buttons on the toolbar to do this (at least bold and
italic). So highlighting some text and pressing the
"bold" button would add "\textbf{" before the text and
"}" after. With no text selected, you would simply get
"\textbf{}". The most obviously useful commands would
be (... = text highlighted):

1. Bold: \textbf{ ... }
2. Italic: \textit{ ... }
3. Superscipt: ^...
4. Subscipt: _...