Completely remove the column cache logic, which has been a persistent source

of bugs for many years.  We recent enhancements to the performance of the
OP_Column opcode, the removing the column cache actually makes speed-check.sh
run faster.  It also saves about 1,800 bytes of code space.

FossilOrigin-Name: 3f5f60cd7529330209027fdae8129cca420cec1050eae50a7750d0b715b56972

test/btree02.test

@@ -33,6 +33,8 @@ do_test btree02-110 {
   db eval BEGIN
   set i 0
   db eval {SELECT a, ax, b, cnt FROM t1 CROSS JOIN t3 WHERE b IS NOT NULL} {
+    if {$a==""} {set a 0}
+    if {$b==""} {set b 0}    
     db eval {INSERT INTO t2(x,y) VALUES($b,$cnt)}
     # puts "a,b,cnt = ($a,$b,$cnt)"
     incr i
@@ -47,6 +49,6 @@ do_test btree02-110 {
     db eval {COMMIT; BEGIN}
   }  
   db one {COMMIT; SELECT count(*) FROM t1;}
-} {20}
+} {27}
 
 finish_test