Allow build output to be received as strings or bytes

Sublime Text 3 r3153 changed the ExecCommand base class to return data as
decoded strings, rather than bytes that need to be decoded. In order to support
both old and new versions of Sublime Text 3, we must support both of these
APIs.

Longer-term, it's probably a good idea to move away from an ExecCommand
subclass.

elm_make.py

@@ -50,7 +50,11 @@ def style_output(self, syntax):
             self.debug_text = get_string('make.missing_plugin')
 
     def on_data(self, proc, data):
-        self.buffer += data
+        # ST3 ExecCommand base class changed from receiving bytes to str
+        if isinstance(data, str):
+            self.buffer += data
+        else:
+            self.buffer += data.decode(self.encoding)
 
     def on_finished(self, proc):
         result_strs = self.buffer.split('\n')

messages/0.22.2.txt

@@ -0,0 +1,3 @@
+New in Elm Language Support 0.22.2 (Mar 24, 2018)
+
+- Fix: Restore build system compatibility with Sublime Text 3 releases prior to r3153.