Update gitignore with generated file patterns

Author: jmtd

.gitignore

@@ -6,4 +6,9 @@ wadc.jar
 wadc.zip
 src/main/resources/git.properties
 .idea/
-*.iml
+*.iml
+gallery/*.html
+gallery/wads
+gallery/img/map_*.png
+examples/*.wad
+doc/*.html