patch 8.2.0111: VAR_SPECIAL is also used for booleans

Problem:    VAR_SPECIAL is also used for booleans.
Solution:   Add VAR_BOOL for better type checking.
diff --git a/src/eval.c b/src/eval.c
index f8ba4df..48357d4 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1246,7 +1246,7 @@
 
     // Can't do anything with a Funcref, Dict, v:true on the right.
     if (tv2->v_type != VAR_FUNC && tv2->v_type != VAR_DICT
-						&& tv2->v_type != VAR_SPECIAL)
+		      && tv2->v_type != VAR_BOOL && tv2->v_type != VAR_SPECIAL)
     {
 	switch (tv1->v_type)
 	{
@@ -1254,6 +1254,7 @@
 	    case VAR_DICT:
 	    case VAR_FUNC:
 	    case VAR_PARTIAL:
+	    case VAR_BOOL:
 	    case VAR_SPECIAL:
 	    case VAR_JOB:
 	    case VAR_CHANNEL:
@@ -3016,6 +3017,7 @@
 		emsg(_(e_float_as_string));
 	    return FAIL;
 #endif
+	case VAR_BOOL:
 	case VAR_SPECIAL:
 	case VAR_JOB:
 	case VAR_CHANNEL:
@@ -3131,6 +3133,7 @@
 	    case VAR_FUNC:
 	    case VAR_PARTIAL:
 	    case VAR_FLOAT:
+	    case VAR_BOOL:
 	    case VAR_SPECIAL:
 	    case VAR_JOB:
 	    case VAR_CHANNEL:
@@ -3777,6 +3780,7 @@
 	    s2 = tv_get_string_buf(tv2, buf2);
 	    return ((ic ? MB_STRICMP(s1, s2) : STRCMP(s1, s2)) == 0);
 
+	case VAR_BOOL:
 	case VAR_SPECIAL:
 	    return tv1->vval.v_number == tv2->vval.v_number;
 
@@ -4531,6 +4535,7 @@
 	    break;
 #endif
 
+	case VAR_BOOL:
 	case VAR_SPECIAL:
 	    *tofree = NULL;
 	    r = (char_u *)get_var_special_name(tv->vval.v_number);
@@ -5359,6 +5364,7 @@
 	    case VAR_NUMBER:
 	    case VAR_FLOAT:
 	    case VAR_UNKNOWN:
+	    case VAR_BOOL:
 	    case VAR_SPECIAL:
 		break;
 	}
@@ -5399,6 +5405,7 @@
 		varp->vval.v_dict = NULL;
 		break;
 	    case VAR_NUMBER:
+	    case VAR_BOOL:
 	    case VAR_SPECIAL:
 		varp->vval.v_number = 0;
 		break;
@@ -5480,6 +5487,7 @@
 	case VAR_DICT:
 	    emsg(_("E728: Using a Dictionary as a Number"));
 	    break;
+	case VAR_BOOL:
 	case VAR_SPECIAL:
 	    return varp->vval.v_number == VVAL_TRUE ? 1 : 0;
 	case VAR_JOB:
@@ -5529,6 +5537,9 @@
 	case VAR_DICT:
 	    emsg(_("E894: Using a Dictionary as a Float"));
 	    break;
+	case VAR_BOOL:
+	    emsg(_("E362: Using a boolean value as a Float"));
+	    break;
 	case VAR_SPECIAL:
 	    emsg(_("E907: Using a special value as a Float"));
 	    break;
@@ -5618,6 +5629,7 @@
 	    if (varp->vval.v_string != NULL)
 		return varp->vval.v_string;
 	    return (char_u *)"";
+	case VAR_BOOL:
 	case VAR_SPECIAL:
 	    STRCPY(buf, get_var_special_name(varp->vval.v_number));
 	    return buf;
@@ -5744,6 +5756,7 @@
     switch (from->v_type)
     {
 	case VAR_NUMBER:
+	case VAR_BOOL:
 	case VAR_SPECIAL:
 	    to->vval.v_number = from->vval.v_number;
 	    break;
@@ -5850,6 +5863,7 @@
 	case VAR_STRING:
 	case VAR_FUNC:
 	case VAR_PARTIAL:
+	case VAR_BOOL:
 	case VAR_SPECIAL:
 	case VAR_JOB:
 	case VAR_CHANNEL: