Refactor error handling for SQLite steps
Refactor error handling for SQLite steps

Moved error handling from the call sites into the Step() wrapper. Simplifies
the call sites (Run(), One()) and adds error handling to other places (All(),
Each()).

roryok/SQLite3-WinRT,roryok/SQLite3-WinRT,roryok/SQLite3-WinRT,roryok/SQLite3-WinRT,doo/SQLite3-WinRT,doo/SQLite3-WinRT,doo/SQLite3-WinRT