Further polish SQLite vendoring

- Now integrated with `make tags` for Emacs IDE features
- Delete some old deprecated broken full-text search engines
- Rename .h → .inc files that don't meet our definition of header
- Make sure every #include line is normal form so tools understand

See #162

third_party/sqlite3/vdbemem.c

@@ -15,8 +15,8 @@
 ** only within the VDBE.  Interface routines refer to a Mem using the
 ** name sqlite_value
 */
-#include "third_party/sqlite3/sqliteInt.h"
-#include "third_party/sqlite3/vdbeInt.h"
+#include "third_party/sqlite3/sqliteInt.inc"
+#include "third_party/sqlite3/vdbeInt.inc"
 /* clang-format off */
 
 /* True if X is a power of two.  0 is considered a power of two here.