Stop classifying "×" (\u00d7) as a lower case letter

Part of #337
Stop classifyinh "÷" (\u00f7) as an upper case letter

Part of #337
Disable wikilinking when preceded with dash or underscore

“HelloThere” in “My-HelloThere” shouldn’t be wikified.

Part of #337
Improved formatting for control panel plugins
Readme update
Docs update
Minor icon tweaks
Docs update
More improvements to control panel plugin formatting