Add source-gen source folder to Ceylon config file

The IDE was complaining about the Ceylon Build Paths being out of sync
with the Ceylon config file.
QualifiedType: Fix documentation typo
Add baseType, qualifiedType utility functions

to easily create a BaseType and QualifiedType respectively without
having to use TypeNameWithTypeArguments.
Add tests for baseType, qualifiedType utility functions

These tests also demonstrate _why_ we need those utility functions.
Add baseExpression, qualifiedExpression functions

to easily create a BaseExpression and QualifiedExpression respectively
without having to use TypeNameWithTypeArguments or
MemberNameWithTypeArguments.
Add tests for baseExpression, qualifiedExpression

These tests also demonstrate why we need these utility functions.
helloworld sample: Use baseExpression() function
RedHatTransformer: Add missing MemberOp

Qualified expressions were missing a MemberOp on the
JQualifiedMemberOrTypeExpression, which crashes the formatter.
(Uncovered by an upgrade to the hello world sample test, to be committed
soon.)
Improve hello world sample

Instead of just saying "Hello, World!", it now greets the first argument
if it exists, defaulting to "World" otherwise.

(Possible after #41 was done. This – to be more precise, the
process.arguments.first part – also uncovered the RedHatTransformer bug
fixed in the previous commit.)