Import miscellaneous dwm patches
Make "xdwm" the default build target instead of "dwm"
Rules for Git ignored files
Use Mod4 (Windows/Cmd) key for keybindings
Apply patches/dwm-5.8.2-swap.diff (aka "swapfocus") patch
Replace dwm -> xdwm in manual page
Update manual page with Mod+s keybinding (swap focus)
Support closing clients with Mod+q

This is convenient with the usage of Mod4 (Windows) key as modifier,
which is the default in xdwm. Also, the fingers feel some strain when
using Mod4+Shift+c to close a window, so this is likely to be better.
Avoid compiler warnings about unused variables
Updated TODO (and converted to devtodo)
xdwm-session: Initial implementation
Gcalctool (GNOME Calculator) floating by default
Copy session/ subdir in dist tarball
Install xdwm-session with execution permission bits
xdwm-session: Ensure existence of ${XDWM_DIR}/log

Ensure that the log directory (${XDWM_DIR}/log) exists before starting drlog
on it.
xdwm-session: Always launch xdwm instead of defaulting to dwm
xdwm-session: Allow setting executable name for service()

The executable name is used to determine whether the program can be
run. If not give, the base name of the first passed argument is
used. Passing it may be needed e.g. when passing options down to
dmon instead of passing the binary path as first argument to
service().
xdwm-session: Properly set the executable name in service()
xdwm-session: Fix comment on PID file location
xdwm-session: Place PID file for xdwm in ${XDWM_DIR}