Add Scientific Calclulator to PanelUI (if available) or addon-bar on firstRun
Improve history box layout.
- Very long variable entries are truncated so the do not blow up the history box's width
- Columns should flex more nicely in most cases
fix "ans" not working in complexMath
Add and option to clear variables and history (by entering the command "clear")
Workaround a Firefox bug that shows a scrollbar in history box for small number of entries despite it would not be necessary
Silence an AMO warning by using "mouseenter" instead of "mouseover"