clang/gcc: enable a bunch more warnings (#91)

* clang/gcc: enable -pedantic warnings

* suppress a GCC-specific warning in stb_image

* And some clang-specific warnings

* -Wconversion (clang) -Wold-style-cast (clang+gcc)

and fix a few warnings that show up with these (and a few more with
-Wconversion on gcc, even though that's not enabled by default)

* bunch more warnings

* fixes

* remove merge error

generator/main.py

@@ -225,7 +225,7 @@ class PreprocessingLoader(jinja2.BaseLoader):
             numstarts = (len(self.blockstart.split(line)) - 1) // 2
             indentation_level += numstarts
 
-        return '\n'.join(result)
+        return '\n'.join(result) + '\n'
 
     def remove_indentation(self, line, n):
         for _ in range(n):