tests: rename files (00x-*.t is basic stuff, >=100-*.t are tests using IPC)

testcases/t/126-regress-close.t

@@ -0,0 +1,18 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Regression: closing of floating clients did crash i3 when closing the
+# container which contained this client.
+#
+use i3test;
+
+fresh_workspace;
+
+cmd 'open';
+cmd 'mode toggle';
+cmd 'kill';
+cmd 'kill';
+
+does_i3_live;
+
+done_testing;