Added a .gitignore.

Author: BradLarson

.gitignore

@@ -0,0 +1,25 @@
+# Exclude the build directory
+build/*
+examples/FilterShowcase/build*
+ 
+# Exclude temp nibs and swap files
+*~.nib
+*.swp
+ 
+# Exclude OS X folder attributes
+.DS_Store
+.svn
+ 
+# Exclude user-specific XCode 3 and 4 files
+*.mode1
+*.mode1v3
+*.mode2v3
+*.perspective
+*.perspectivev3
+*.pbxuser
+*.xcworkspace
+xcuserdata
+
+# Documentation
+documentation/*
+