Add align commands (left, center, right)

[osv]

Added ^left(), ^center(), and ^right() commands.
With these commands, there's no longer a need to run multiple instances of dzen2 or use the -expand parameter.

Each new command will copy pixmap to window and call parse_line with rest of not processed text.

Demo:

#!/usr/bin/env bash

# nano dark theme
FOREGROUND="#ECEFF4"  # white
BACKGROUND="#2E3440"  # black
HIGHLIGHT="#3B4252"   # brightblack
SUBTLE="#434C5E"      # brightblack
FADED="#677691"       # cyan
SALIENT="#81A1C1"     # brightblue
STRONG="#FFFFFF"      # brightwhite
POPOUT="#D08770"      # brightred
CRITICAL="#EBCB8B"    # yellow


fg="^fg($FOREGROUND)"
bg="^fg($BACKGROUND)"
sep="^fg($FADED)|"
active="^bg($POPOUT)^fg($BACKGROUND)"

key="^fg($SALIENT)"
val="^fg($STRONG)"

left="^left()${bg}$fg 1 $sep $fg 2 $sep $active 3 "
center="^center()${fg}12:34"
right="^right()$key CPU:$val 10% $sep $key MEM:$val 3.3GB"

echo " ${left}${center}${right} " | ./dzen2 -p -fn "Iosevka Comfy-12" -w 800 -bg $BACKGROUND -fg $FOREGROUND

My fork includes graphical unit tests, and no regressions have been detected.