Improve Pan language support (#3691)

* Add a larger set of sample files for Pan

This is a fairly good cross section of Pan based on code from:
* https://github.com/quattor/template-library-examples
* https://github.com/quattor/template-library-core

* Add Pan language grammar

samples/Pan/mysql.pan

@@ -0,0 +1,29 @@
+unique template common/opennebula/mysql;
+
+prefix "/software/packages";
+"{mysql-server}" = dict();
+
+include 'components/mysql/config';
+
+prefix  "/software/components/mysql";
+"serviceName" = {
+    if (RPM_BASE_FLAVOUR_VERSIONID == 7) {
+        "mariadb";
+    } else {
+        "mysqld";
+    };
+};
+prefix "/software/components/mysql/servers/one";
+"host" = FULL_HOSTNAME; # localhost is added by component
+"adminpwd" = OPENNEBULA_MYSQL_ADMIN;
+"adminuser" = "root";
+
+prefix "/software/components/mysql/databases/opennebula";
+"server" = "one";
+"users/oneadmin/password" = OPENNEBULA_MYSQL_ONEADMIN;
+"users/oneadmin/rights" = list("ALL PRIVILEGES");
+"createDb" = false; # if false, run script
+"initScript/file" = "/dev/null";
+
+prefix "/software/components/chkconfig/service";
+"mysqld" = dict("on", "", "startstop", true);