Have fts5 cache the structure of its index in main memory. Use "PRAGMA data_version...

FossilOrigin-Name: 902f221754f3cc6fb4ae049c135f85efce604ed3

diff --cc ext/fts5/fts5_index.c
Simple merge

diff --cc ext/fts5/fts5_storage.c
Simple merge

diff --cc manifest
index 6c35067176c776595b0fb51866af82c8ba2537a7,65691a0210fae473cb5478bb12f67078c8911763..5d26916c17466c97e39b6e1b4bb9459792a37754
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Add\sthe\ssqlite3_system_errno()\sinterface.
- D 2016-03-21T14:46:37.265
 -C Rearrange\scode\sso\sthat\stests\spass\swhether\sSQLITE_DEBUG\sis\sdefined\sor\snot.
 -D 2016-03-21T15:18:13.028
++C Have\sfts5\scache\sthe\sstructure\sof\sits\sindex\sin\smain\smemory.\sUse\s"PRAGMA\sdata_version"\sto\sfigure\sout\swhen\sthis\scache\sshould\sbe\sinvalidated.
++D 2016-03-21T15:30:50.247
  F Makefile.in f53429fb2f313c099283659d0df6f20f932c861f
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
  F Makefile.msc df0bf9ff7f8b3f4dd9fb4cc43f92fe58f6ec5c66
@@@ -104,9 -104,9 +104,9 @@@ F ext/fts5/fts5_buffer.c 4c1502d4c956cd
  F ext/fts5/fts5_config.c 5af9c360e99669d29f06492c370892394aba0857
  F ext/fts5/fts5_expr.c 35e9d92c89e7c7ea0759b73d24da1ecb7630a24b
  F ext/fts5/fts5_hash.c f3a7217c86eb8f272871be5f6aa1b6798960a337
- F ext/fts5/fts5_index.c d3759c2f7d878e9e0a392b027a1c6e05c356007d
- F ext/fts5/fts5_main.c b8501e1a6a11591c53b18ce7aea7e5386cfb0421
- F ext/fts5/fts5_storage.c 2a38c6fa5db193a6a00588865134450ef5812daa
 -F ext/fts5/fts5_index.c 39939320ee5185cbfd0a8c8c7e1c878ebde7c43d
++F ext/fts5/fts5_index.c 40fde2538deeb7f018435c1d1bacf057f89c3c42
+ F ext/fts5/fts5_main.c b4a0fc5bf17f2f1f056ee76cdd7d2af08b360f55
 -F ext/fts5/fts5_storage.c a3361410422e69639ca2bcd5a56a0933dadf84d2
++F ext/fts5/fts5_storage.c 98e3129047d250fc5acc4a4ba7ba4fde9b0ae030
  F ext/fts5/fts5_tcl.c f8731e0508299bd43f1a2eff7dbeaac870768966
  F ext/fts5/fts5_test_mi.c 783b86697ebf773c18fc109992426c0173a055bc
  F ext/fts5/fts5_test_tok.c db08af63673c3a7d39f053b36fd6e065017706be
@@@ -1457,8 -1457,7 +1458,7 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P d6e2637df16764aa9723a30ea2eb8a631d28cb2b b4a1114f730c62e93623f889bc0e4fd8d0b31efa
- R 6870e1f7d1e452978a882de2dd2b0506
- T +closed b4a1114f730c62e93623f889bc0e4fd8d0b31efa
- U drh
- Z c933d47fc520e2ff9b51b35972ce646c
 -P 7832466f9177cca59455ba272802145297fcd53d
 -R e2f3ffc019af1c2320d4d618c0233909
++P 4bd12b57ea177cfb1f44d54bfa7aedfb8a8c0c64 89296a46c3b891ee0b637ff6f89d828d6e46e7b5
++R 81b99f33bb0a77bc5e744352db10978f
+ U dan
 -Z 04b6e502bb8ccbe0b89bf7d08daf8ee8
++Z db5fc495668353fb57116ffc2b5d2027

diff --cc manifest.uuid
index f6b0ceae980fe3f17a2dcb5fdceac5b3c113d7c6,62bde4070e1002827fbe5e5144413f0f0974013e..fb9fd2a351112cb2bef37c9f47268e90626bd1ef
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 4bd12b57ea177cfb1f44d54bfa7aedfb8a8c0c64
 -89296a46c3b891ee0b637ff6f89d828d6e46e7b5
++902f221754f3cc6fb4ae049c135f85efce604ed3