Add show effects preference

Added preference to show textual styling (referred to as "effects"
in the source code), including: bold, italics, underline,
foreground colors, and background colors. When the preference is
disabled users' messages will be stripped of additional formatting.
Use stripMIRCEffects for Show effects preferences

Utilize the stripMIRCEffects method to ensure stripping of mIRC
style colors.
Remove extraneous space
Merge branch 'showeffects' of https://github.com/thomdixon/limechat