QRegExp matching is quite expensive, and has to be done for every file
in the project directory tree against all possible suffixes. Optimize
for the common case that the pattern is "*.suffix" by doing a
fileName.endsWidth(suffix) in this case.

This speeds up loading of examples/declarative/declarative.qmlproject by
about 30%.

Reviewed-by: Christian Kamm

E.g. "QmlFiles {}" now also monitors subdirectories by default, while
"QmlFiles { paths : ["bla.qml"] } does not.

Task-number: BAUHAUS-503

Suggested by Erik Verbruggen

Instead of letting the list of files being a (comma separated) string
it's now a full JavaScript array. E.g.

  paths: ["file1", "file2"]

This unifies it with e.g. the libraryPaths property

Check for the case that a new file to be added to a .qmlproject
is also automatically covered e.g. by a wildcard filter. In this
case we don't have to do anything.

Will be passed to qmlviewer with the "-L" option. Storing this in
the .qmlproject file format itself (and not in the .user file) is useful
in case the libraries are relative/part of the checkout that is shared
between users/computers.

We're converting the path to absolute ones in QmlProject anyway ...