Updated README.md and did a re-sync.

.gitignore

@@ -1,9 +1,37 @@
-# Used by IntelliJ CLion
-.idea
-CMakeLists.txt
-
-#used by MSVC
-**/*.aps
-src/win/msvc15/.vs/
-src/win/msvc15/Debug/
-src/win/msvc15/Release/
+# Used by GIT.
+.gitignore
+# Used by Code::Blocks
+src/win/codeblocks/*
+# Used by MSVC.
+src/win/msvc/.depends
+src/win/msvc/vc*/.vs/
+src/win/msvc/vc*/Debug/
+src/win/msvc/vc*/Release/
+# Used by MinGW
+src/win/mingw/.depends
+# Used by the UNIX backends.
+src/unix
+src/unix/.depends*
+src/unix/*
+# Used by the WxWidgets backend.
+src/wx
+src/wx/*
+# Used by the Qt backend.
+src/qt
+src/qt/*
+# Standard folders.
+roms
+roms/*
+vm
+vm/*
+# Local stuff, unsorted etc.
+src/Makefile
+src/waltje
+src/waltje/*
+# Other files.
+src/*.obj
+src/*.d
+src/*.o
+src/*.exe
+src/*.res
+src/*.map