resurrecting xcodeproj, fix gitignore

.gitignore

@@ -14,19 +14,74 @@
 # Doxygen output
 doxygen_out/
 
-# Mac Stuff
+# mac
 .DS_Store
-*.swp
-*~.nib
-*.build/
-DerivedData/
-Debug/
 
-*.xcodeproj/
-!*.xcodeproj/project.pbxproj
+#####
+# Xcode private settings (window sizes, bookmarks, breakpoints, custom executables, smart groups)
+#
+# This is complicated:
+#
+# SOMETIMES you need to put this file in version control.
+# Apple designed it poorly - if you use "custom executables", they are
+#  saved in this file.
+# 99% of projects do NOT use those, so they do NOT want to version control this file.
+#  ..but if you're in the 1%, comment out the line "*.pbxuser"
 
+*.pbxuser
 *.mode1v3
 *.mode2v3
+*.perspectivev3
+#    NB: also, whitelist the default ones, some projects need to use these
+!default.pbxuser
+!default.mode1v3
+!default.mode2v3
+!default.perspectivev3
+
+
+####
+# Xcode 4 - semi-personal settings, often included in workspaces
+#
+# You can safely ignore the xcuserdata files - but do NOT ignore the files next to them
+#
+
+xcuserdata
+
+####
+# XCode 4 workspaces - more detailed
+#
+# Workspaces are important! They are a core feature of Xcode - don't exclude them :)
+#
+# Workspace layout is quite spammy. For reference:
+#
+# (root)/
+#   (project-name).xcodeproj/
+#     project.pbxproj
+#     project.xcworkspace/
+#       contents.xcworkspacedata
+#       xcuserdata/
+#         (your name).xcuserdatad/
+#           WorkspaceSettings.xcsettings
+#     xcuserdata/
+#       (your name).xcuserdatad/
+#         xcschemes/
+#           (project-name).xcscheme
+#
+#
+#
+# Xcode 4 workspaces - SHARED
+#
+# This is UNDOCUMENTED (google: "developer.apple.com xcshareddata" - 0 results
+# But if you're going to kill personal workspaces, at least keep the shared ones...
+#
+#
+!xcshareddata
+
+####
+# XCode 4 build-schemes
+#
+# PRIVATE ones are stored inside xcuserdata
+!xcschemes
 
 # Visual Studio 2012
 *.sdf