Module for reading Xresource config options
Use xrm module to pass config options to classes
Bugfix: need to take size of value, not address
Introduce new xrm value type: double

* Use switch-case for type casting
* Use pointer to std::string instead of char * for strs
Add default c'tor to allow for empty objects
Rename value member to v
Take {un,}focused border color as hex string + additional alpha value
Take additional borderwidth & iconsize config values
Make title configurable (fonts, {fb,bg}color)
Messed up order of options
Actually convert hex colors to proper double values

substr(pos, size) <- this is *size*, not end!

Conversion of #abcdef means:
Take [1,2] (e.g.: "ab"), convert it to dec (ab -> 171) and calculate the
double fraction for the 16bit color value: 171/255
unordered_set has no member called remove()..
Make xrm an observable
x::xrm::update_db() function to reload database entries
x::xrm::release_db() for freeing allocated resources
'Read X resource manager string directly from atom

Xlib function will read it only once on program start
update db when RESOURCE_MANAGER property changes & notify observers
Instatiate xrm with x_connnection instead of Display
Move config setup code to own method
Move config setup code to own method