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/vdbevtab.c

@@ -13,9 +13,9 @@
 ** This file implements virtual-tables for examining the bytecode content
 ** of a prepared statement.
 */
-#include "third_party/sqlite3/sqliteInt.h"
+#include "third_party/sqlite3/sqliteInt.inc"
 #if defined(SQLITE_ENABLE_BYTECODE_VTAB) && !defined(SQLITE_OMIT_VIRTUALTABLE)
-#include "third_party/sqlite3/vdbeInt.h"
+#include "third_party/sqlite3/vdbeInt.inc"
 /* clang-format off */
 
 /* An instance of the bytecode() table-valued function.