patch 8.0.0661: recognizing urxvt mouse codes does not work well

Problem:    Recognizing urxvt mouse codes does not work well.
Solution:   Recognize "Esc[*M" and "Esc[*m". (Maurice Bos, closes #1486)
diff --git a/src/keymap.h b/src/keymap.h
index 776a532..10264ae 100644
--- a/src/keymap.h
+++ b/src/keymap.h
@@ -112,6 +112,7 @@
 
 /* Used for the sgr mouse. */
 #define KS_SGR_MOUSE		237
+#define KS_SGR_MOUSE_RELEASE		236 /* Release */
 
 /*
  * Filler used after KS_SPECIAL and others
@@ -416,6 +417,7 @@
 #define K_PTERM_MOUSE	TERMCAP2KEY(KS_PTERM_MOUSE, KE_FILLER)
 #define K_URXVT_MOUSE	TERMCAP2KEY(KS_URXVT_MOUSE, KE_FILLER)
 #define K_SGR_MOUSE	TERMCAP2KEY(KS_SGR_MOUSE, KE_FILLER)
+#define K_SGR_MOUSERELEASE TERMCAP2KEY(KS_SGR_MOUSE_RELEASE, KE_FILLER)
 
 #define K_SELECT	TERMCAP2KEY(KS_SELECT, KE_FILLER)
 #define K_TEAROFF	TERMCAP2KEY(KS_TEAROFF, KE_FILLER)