Change order of theme loading

The base theme is now loaded after plugins, since it now uses the
`command_exists` function, which is defined in the `base` plugin.

bash_it.sh

@@ -34,10 +34,6 @@ source "${BASH_IT}/lib/composure.bash"
 # support 'plumbing' metadata
 cite _about _param _example _group _author _version
 
-# Load colors first so they can be use in base theme
-source "${BASH_IT}/themes/colors.theme.bash"
-source "${BASH_IT}/themes/base.theme.bash"
-
 # libraries, but skip appearance (themes) for now
 LIB="${BASH_IT}/lib/*.bash"
 APPEARANCE_LIB="${BASH_IT}/lib/appearance.bash"
@@ -54,6 +50,10 @@ do
   _load_bash_it_files $file_type
 done
 
+# Load colors first so they can be used in base theme
+source "${BASH_IT}/themes/colors.theme.bash"
+source "${BASH_IT}/themes/base.theme.bash"
+
 # appearance (themes) now, after all dependencies
 source $APPEARANCE_LIB