Fix for qOverload and git ignore a bunch of intermediates

1. Change compiler req to c++14 because thats what qOverload needs
2. Add a bunch of intermediate files into the .gitignore

Author: uvatbc

.gitignore

@@ -1,4 +1,11 @@
 *CMakeLists.txt.user
 _build/
 *.DS_Store
-o2.pro.user
+o2.pro.user
+
+# Intermediates
+.qmake.stash
+Makefile
+*.o
+moc_*
+libo2.so*

o2.pro

@@ -9,7 +9,7 @@ TEMPLATE = lib
 DEFINES += O2_SHARED_LIB
 DEFINES += O2_DLL_EXPORT
 
-CONFIG += c++11
+CONFIG += c++14
 
 # The following define makes your compiler emit warnings if you use
 # any Qt feature that has been marked deprecated (the exact warnings