experimental RTL support features (schema, version bump)

schema/upgrade-1.1.4-1.1.5-mysql.sql

@@ -0,0 +1,9 @@
+alter table ttrss_feeds add column rtl_content bool;
+
+update ttrss_feeds set rtl_content = false;
+
+alter table ttrss_feeds change rtl_content rtl_content bool not null;
+alter table ttrss_feeds alter column rtl_content set default false;
+
+update ttrss_version set schema_version = 7;
+