- `.from(t1, t2)` produces an unconditional join if you forget to add a condition in the .where()
sqlpp11 therefore now deprecates unconditional joins.
- more often than not, writing something like `where(name == "doe")`, you
meant to write `where(t.name == "doe")`. It is hard to find bugs when
the former expression compiles because you happen to have a variable
`name` in the current scope as well.
sqlpp11 therefore now deprecates `.where(bool)` and disallows
raw bool values boolean expression like `something and bool`
wrap bools in sqlpp::value(), if you REALLY want a bool value here
