operator== for rectangle
Method to query screen dimensions of primary output (XRandr)
Scrub non printable characters from resource value string

Change isalnum to isprint.
isprint allows also space (' ') and other characters like '#' '%', etc.

> http://en.cppreference.com/w/cpp/string/byte/isprint
Return absolute window position
Use translate coordinates request to find parent window; more efficient than query tree
New configuration value for setting the screen for showing thumbnails
Different functions for finding the screen for showing thumbs
Use configuration variable to decide on which screen to display thumbnails
Revert "Use translate coordinates request to find parent window; more efficient than query tree"

This reverts commit bb6dd3c3a1685c30a22e3038fad27fc823c025bf.

This was a bad idea. Returns the wrong children for windows in the same
position (through stacking).
PKGBUILD.in is a template
VERSION is the template variable for sed
Automate package release to AUR
Add a target to automate releases
Interface for configuration value & adapter to merge config_t objects
Rename config -> gl_config (namespace)
Replace xrm config object with generic::config_t interface
Need to do this everytime, since the config might have change in the meantime
Use generic::config_t enums
Use push_back to make behaviour more understandable
Recursion needs to be actually unfold somewhere