IITC theme / ui structure (internal)

[johnd0e]

1. IITC colors are ugly.
   I hate background color most of all.
   Shouldn't we use default palette from Ingress intel?

2. IITC css is chaotic.
   Currently in order to overdrive background I need to redefine a bunch of styles independently (instead of change just one value)

3. IITC UI elements themselves are placed without proper hierarchy.
   E.g. #sidebartoggle is not a part of #sidebar (or #scrollwrapper).
   #chat and #chatcontrols are also independent elements.
   So it's hard to theme them as whole part, and we get issues trying to change placing or scaling properties.

4. It's a common case in IITC if some complex element get completely cleared (or replaced, with all sub-elements). It's also undesirable in some cases, and it may be better to hide instead of clear (and update sub-elements individually, instead or rewriting whole parent element).

[johnd0e]

Related: #466