Better error position when EXML compiler exception does not specify a file:
at least point to the source file or the module file where the error occurred.
Notify the user (via bubble / Event Log) when a Maven project contains
a module with packaging "jangaroo", but no jangaroo- or exml-maven-plugin
can be found. This can happen for new modules with complex structure
(parent POMs, import of BOM POMs) and is usually "healed" by simply
trying again.