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

@@ -1,27 +1,52 @@
 #!/bin/sh
 
-wget -O /tmp/nanorc.zip https://github.com/scopatz/nanorc/archive/master.zip
-if [ ! -d ~/.nano/ ]
-then
+function _fetch_sources() {
+  wget -O /tmp/nanorc.zip https://github.com/scopatz/nanorc/archive/master.zip
+  if [ ! -d ~/.nano/ ]
+  then
     mkdir ~/.nano/
-fi
+  fi
 
-cd ~/.nano/
+  cd ~/.nano/
 
-unzip -o "/tmp/nanorc.zip"
-mv nanorc-master/* ./
-rm -rf nanorc-master
-rm /tmp/nanorc.zip
+  unzip -o "/tmp/nanorc.zip"
+  mv nanorc-master/* ./
+  rm -rf nanorc-master
+  rm /tmp/nanorc.zip
+}
 
-if [ ! -f ~/.nanorc ]
-then
+function _update_nanorc() {
+  if [ ! -f ~/.nanorc ]
+  then
       touch ~/.nanorc
-fi
+  fi
 
-# add all includes from ~/.nano/nanorc if they're not already there
-NANORC_FILE=~/.nanorc
-while read inc; do
+  # add all includes from ~/.nano/nanorc if they're not already there
+  while read inc; do
       if ! grep -q "$inc" "${NANORC_FILE}"; then
           echo "$inc" >> $NANORC_FILE
       fi
-done < ~/.nano/nanorc
+  done < ~/.nano/nanorc
+}
+
+function _update_nanorc_lite() {
+  sed -i '/include "\/usr\/share\/nano\/\*\.nanorc"/i include "~\/.nano\/*.nanorc"' "${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