Revert "Show floating clients with a "pressed" title bar"

This reverts commit a21a42677908f28a6301bec9fd8de8bcdb00bf7f.

A "pressed title bar" looks horrible with most GUI applications. Every
dialog is floating...
Mark floating clients with a little square

Just like it was done in the bar once.
Print a warning if there's no SHAPE extension
Dummy variables
Colors/fonts: Clean up various messy places
Move color and font info into their own structs
Make dc.gc and dc.drawable pointers, add BarContext
setborder() uses drawtext() and drawsquare()
Kick black rectangle when there's no SHAPE extension

If that extension is not available, everything will look crappy anyway.
There's no benefit in drawing a black border...