QVT — Chapter 7 QVTrelation Standard Library

There is a QVT Standard Library in Chapter 8, that the Pre-ballot 2 FTF report describes
as the QVT Operational Standard Library.

QVTrelation requires a library that at least defines:
String::+ as a synonym for String::concat

That part of the Chapter 8 library that is common to all QVT languages should appear in
its own chapter along with other parts of QVT that are common e.g. QVTbase.

Add the following subsection in the concrete syntax section 7.13:

Shorthands used to invoke pre-defined operations
The binary operator "+" can be used as shorthand for the string concat operation.