refactor replacing go-llsqlite/crawshaw with mattn/go-sqlite3

[evrins]

tried replacing go-llsqlite/crawshaw with mattn/go-sqlite3
have to add compile tag nosqlite to disable go-llsqlite/crawshaw in torrent lib to make it compile or duplicate symbol erorr may occur

go-llsqlite/crawshaw in torrent is used for piece completion storage, since we have implemented , it is ok to disable it.

this change will increase binary size by 2 Mib on my mac

mattn/go-sqlite3 is database/sql compatible, we can use with pgx to reduce duplicate code

with SetMaxOpenConns(1) we can remove locked in every function call and will not trigger database is locked error

code is on branch refactor/migrate_to_mattn_go-sqlite3

@varbhat