Add standard .gitattributes

Used to make sure that "non-windows" files don't get Windows line
endings added amongst other functionality.

.gitattributes

@@ -0,0 +1,17 @@
+[attr]pony text eol=lf whitespace=tab-in-indent,trailing-space,tabwidth=2
+[attr]win  text eol=crlf whitespace=tab-in-indent,trailing-space,tabwidth=2
+
+*.c pony
+*.cc pony
+*.h pony
+*.pony pony
+*.yml pony
+*.sh pony
+*.bash pony
+
+*.bat win
+
+.gitattributes export-ignore
+.gitignore export-ignore
+
+CHANGELOG.md merge=union