Fts: Compatible 2.3
Fix mispelt
Fix uncaught SQLiteDoneException
existVirtualTable: Remove unnecessary try
Rename existVirtualTable to existsTable
Move existTable() into createVirtualTable
Revert "Move existTable() into createVirtualTable"

This reverts commit a6d9afdd667e4147746bf70f28f2f216d797128a.
imple
Support executeAlter but its disabled now