sql: display line and position in syntax errors

When it comes for huge queries, it may turn out to be useful to see
exact position of occurred error. Hence, let's now display line and
position within line near which syntax error takes place. Note that it
can be done only during parsing process (since AST can be analysed only
after its construction is completed), so most of semantic errors still
don't contain position. A few errors have been reworked to match new
formatting patterns.

First iteration of this patch is implemented by @romanhabibov

Closes #2611