drop 3.4 compatibility

.travis.yml

@@ -5,12 +5,7 @@ dist: trusty
 
 haxe:
   - development
-  - "3.4.7"
-  - "4.0.0-rc.4"
-
-#matrix:
-#  allow_failures:
-#    - haxe: "3.4.7"
+  - "4.0.0-rc.5"
 
 install:
   - yes | haxelib install all