Refactor the OP_Column opcode to make it clearer and easier to maintain.

Overall, performance tests show about a 1% speed increase with this change.

FossilOrigin-Name: 972881c6d394c199961f01dcbeb4a6e8b5c919a1

diff --cc manifest
index 0b494c9b3bd1ed3ff37fc3f7bd8ec4d48ea1c0b0,667c92d94a48b78ba892b0e3f9d3276b1170873b..27f372c5626710a1419f3a74286243e781dca130
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Simplifications\sto\sthe\sVdbeCursor\sobject.
- D 2013-11-20T02:53:58.741
 -C Reduce\sthe\ssize\sof\sVdbeCursor\sagain,\sthis\stime\swithout\sa\sperformance\shit.
 -D 2013-11-21T01:04:02.826
++C Refactor\sthe\sOP_Column\sopcode\sto\smake\sit\sclearer\sand\seasier\sto\smaintain.\nOverall,\sperformance\stests\sshow\sabout\sa\s1%\sspeed\sincrease\swith\sthis\schange.
++D 2013-11-21T01:33:45.684
  F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
  F Makefile.in 8a07bebafbfda0eb67728f4bd15a36201662d1a1
  F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@@ -1140,7 -1140,7 +1140,8 @@@ F tool/vdbe-compress.tcl f12c884766bd14
  F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
  F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
  F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
- P 96a65388e75fed96e2e73ef65726f6db88cc5ccd
- R ca796b6fcdb020d784b4cd61fedf5893
 -P f8d5efcd7b92492b833b6cd1cb6bec006c6a0809
++P 5562cd343d8f69242e06a51a7f1aef7ee7d78eec 933939932c44bccb0958f203a5bd24e683c1cf38
+ R 842b8e02c5c12ba51889f25ba6cef74b
++T +closed 933939932c44bccb0958f203a5bd24e683c1cf38
  U drh
- Z 97e722e14aa88f975fca1769e7e16ee6
 -Z a21060677c94bf6a3d8120f6bac96f14
++Z 16455d71573d7ca0de3f10177a1e6082

diff --cc manifest.uuid
index 27fbbf3bcd58700169f414be38bbcf841b8aa7f6,8232c536847a6e34209878eac1bba7bb6b58b222..29bb141912495f676481659d28c0d50704417fe5
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 5562cd343d8f69242e06a51a7f1aef7ee7d78eec
 -933939932c44bccb0958f203a5bd24e683c1cf38
++972881c6d394c199961f01dcbeb4a6e8b5c919a1