Add -l|--lite option to install which includes new syntax files with lower precedence

Readme.rst

@@ -32,3 +32,8 @@ Finally, you can run an automatic installer using the following code::
 or alternatively::
 
     $ wget https://raw.githubusercontent.com/scopatz/nanorc/master/install.sh -O- | sh
+
+*Note -
+    some syntax definitions which exist in Nano upstream may be preferable to the ones provided by this package.
+    The install.sh script may be run with ``-l`` or ``--lite`` to insert the included syntax definitions from this package
+    with lower precedence than the ones provided by the standard package.

install.sh

@@ -1,5 +1,6 @@
 #!/bin/sh
 
+function _fetch_sources() {
   wget -O /tmp/nanorc.zip https://github.com/scopatz/nanorc/archive/master.zip
   if [ ! -d ~/.nano/ ]
   then
@@ -12,16 +13,40 @@ unzip -o "/tmp/nanorc.zip"
   mv nanorc-master/* ./
   rm -rf nanorc-master
   rm /tmp/nanorc.zip
+}
 
+function _update_nanorc() {
   if [ ! -f ~/.nanorc ]
   then
       touch ~/.nanorc
   fi
 
   # add all includes from ~/.nano/nanorc if they're not already there
-NANORC_FILE=~/.nanorc
   while read inc; do
       if ! grep -q "$inc" "${NANORC_FILE}"; then
           echo "$inc" >> $NANORC_FILE
       fi
   done < ~/.nano/nanorc
+}
+
+function _update_nanorc_lite() {
+  sed -i '/include "\/usr\/share\/nano\/\*\.nanorc"/i include "~\/.nano\/*.nanorc"' "${NANORC_FILE}"
+}
+
+NANORC_FILE=~/.nanorc
+
+case "$1" in
+ -l|--lite)
+ UPDATE_LITE=1;;
+ -h|--help)
+ echo "Install script for nanorc syntax highlights"
+ echo "Call with -l or --lite to update .nanorc with secondary precedence to existing .nanorc includes"
+ ;;
+esac
+
+_fetch_sources;
+if [[ $UPDATE_LITE ]]; then
+  _update_nanorc_lite;
+else
+  _update_nanorc;
+fi