Added battery charge gauge from: http://stevelosh.com/blog/2010/02/my-extravagant-zsh-prompt/ to themes

Battery gauge requires a python script, 'battcharge.py' added to $ZSH/lib/ directory to work properly.
Cleaned up zshmarks again, now uses proper return codes in case bookmark not found, etc.

lib/battcharge.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+# coding=UTF-8
+
+import math, subprocess
+
+p = subprocess.Popen(["ioreg", "-rc", "AppleSmartBattery"], stdout=subprocess.PIPE)
+output = p.communicate()[0]
+
+o_max = [l for l in output.splitlines() if 'MaxCapacity' in l][0]
+o_cur = [l for l in output.splitlines() if 'CurrentCapacity' in l][0]
+
+b_max = float(o_max.rpartition('=')[-1].strip())
+b_cur = float(o_cur.rpartition('=')[-1].strip())
+
+charge = b_cur / b_max
+charge_threshold = int(math.ceil(10 * charge))
+
+# Output
+
+total_slots, slots = 10, []
+filled = int(math.ceil(charge_threshold * (total_slots / 10.0))) * u'▸'
+empty = (total_slots - len(filled)) * u'▹'
+
+out = (filled + empty).encode('utf-8')
+import sys
+
+color_green = '%{%}'
+color_yellow = '%{%}'
+color_red = '%{%}'
+color_reset = '%{%}'
+color_out = (
+    color_green if len(filled) > 6
+    else color_yellow if len(filled) > 4
+    else color_red
+)
+
+out = color_out + out + color_reset
+sys.stdout.write(out)