Moar fixes to sourcerers.

DEBUG variable force in config loader. If variable isn't defined - force it to be 0.

zsh/05-vars.zsh

@@ -2,4 +2,12 @@
 # this configuration.
 
 OS=`uname`
-OS_RELEASE=`uname -r`
+OS_RELEASE=`uname -r`
+
+# Variable forcers.
+
+# If DEBUG isn't defined - force it to be 0.
+if [ -z ${DEBUG} ]; then
+    DEBUG=0
+    return 1
+fi