Revert "Update tcell to use gdamore's fix for idle wakeup"

This reverts commit f01ad3f726701349a2de24ae2e3fcf663f273ee3.

diff --git a/cmd/micro/vendor/github.com/zyedidia/tcell b/cmd/micro/vendor/github.com/zyedidia/tcell
index a221f2faf4f9a059c8eba8f91c5d0dbd9845a985..c47e75564a5c5e7fb5c7e5ec5b341c7902d551bc 160000 (submodule)
--- a/cmd/micro/vendor/github.com/zyedidia/tcell
+++ b/cmd/micro/vendor/github.com/zyedidia/tcell
@@ -1 +1 @@
-Subproject commit a221f2faf4f9a059c8eba8f91c5d0dbd9845a985
+Subproject commit c47e75564a5c5e7fb5c7e5ec5b341c7902d551bc