Fix maven build configuration, include MWE2 workflow execution for xtext generation

[JKatzwinkel]

Multiple modifications turned out to be necessary in order to get maven build to work on a fresh clone. Most importantly, though, execution of mwe2 workflow xtend script for xtext generation of egyptian transliteration notation grammar could be integrated into the build process.

This is a major improvement because so far, generation of the grammar code had to be run in eclipse in order to be able to build the application. Now everybody can build BTS without even having eclipse.

[JKatzwinkel]

Execution of EMF MWE2 workflow for code generation from xtext grammar successfully could be invoked by maven configuration when attribute classpathScope of plugin exec-maven was set to compile. Contrary to assertions in its documentation, this plugin uses default value runtime. Furthermore, classpath needs to be specified using classpath magic tag <classpath/>. This allows MWE workflow to interprete resource locators correctly. Resulting configuration in org.bbaw.bts.corpus.text.egy.egydsl/pom.xml:

            <configuration>
                <includeProjectDependencies>true</includeProjectDependencies>
                <includePluginDependencies>true</includePluginDependencies>
                <!-- necessary for the java process to find the mwe2 launcher -->
                <classpathScope>compile</classpathScope>
                <executable>java</executable>
                <arguments>
                    <!-- necessary for the java process to find the mwe2 launcher -->
                    <argument>-classpath</argument>
                    <classpath/>
                    <argument>org.eclipse.emf.mwe2.launch.runtime.Mwe2Launcher</argument>
                    <argument>file://${project.basedir}/src/org/bbaw/bts/corpus/text/egy/GenerateEgyDsl.mwe2</argument>
                </arguments>
              </configuration>

[JKatzwinkel]

Added Travis build status bagde:

[JKatzwinkel]

There is a problem with the editor part because for some reason EgyDslRuntimeModule can't be resolved in clean builds even though it exists in org.bbaw.bts.corpus.text.egy.egydsl.