Merge tag '0.16' into develop

Major overhaul of internal structures

The most important change is that there is a generic statement now.
A statement is a variadic template with the clauses as template arguments.
This makes it very easy to add features to statements, e.g. to mimic specific dialects.

Removed namespace vendor.

Removed direct support for char-based results. This was rather vendor specific and
is therefore to be implemented by the connector libraries, if required.

Lots of smaller changes and corrections.
Adjusted api to recent changes.
Merge branch 'master' of https://github.com/rbock/sqlpp11
Adjusted api to recent changes.
Update README.md

Link to Matthijs' postgresql connector and minor updates in the examples
Added blob (currently synonym of text)
Made generated file available by default

This lowers the threshold for those without python.
Update README.md

Added links to wiki and container backend.
Merge branch 'release/0.17'

Conflicts:
	README.md