Added .gitignore

.gitignore

@@ -0,0 +1,16 @@
+# ------- main .gitgnore -------
+# ignore everything
+*
+# except .gitignore
+!.gitignore
+
+
+# ------- k&r .gitignore -------
+# except k&r
+!k\&r/
+# except chapters
+!k\&r/[0-9]*/
+# and excercise solutions
+!k\&r/*/[0-9]*.c
+# and header files
+!k\&r/*/*.h