Introduce a mechanism for parsing the YAML.

This allows the configuration to be able to refer to modules by name -
for example, when applying the web compiler; so the source can be moved
around more easily.

Signed-off-by: Nigel Magnay <nigel.magnay@gmail.com>
Allow easy instantiation of the dart web compiler.

This can be acheived with the following configuration :

<execution>
   <id>compile</id>
   <configuration>
      <packageName>daterop_web</packageName>
      <output>web/out/</output>
      <htmlFile>web/darterop.html</htmlFile>
   </configuration>
   <goals>
      <goal>dwc</goal>
   </goals>
</execution>

This would normally be followed by a traditional dart2js config.


Signed-off-by: Nigel Magnay <nigel.magnay@gmail.com>