Most users are not to be expected to be familiar with
sqlite's FTS syntax. It also leads to unnnecessary
arrows in some instances.
So wrap every space separated word in quotes, unless
it's already in quotes. Then we just escape those with
double-quotes.
Purpose is to seperate certain logic from SQLite and generalize it more.
Even though we only have Sqlite atm, in general the database layers
must be stupid as possible, while QSSQuery should do most of the hard work.
Fixes in Tokenizer logic.
Switched to C++17.
