Clean PDF plug-in stylesheet

* Remove obsolete comments
* Add datatypes
Fix build script to work with new docs build
Add datatypes to variable and template in mappull XSLT
Move message configuration file to dost-configuration.jar

The messages.xml file should not be included in dost.jar as it is not
regenerated during integration. The dost-configuration.jar is intended
for configuration files and files that are generated during integration.
Treat missing filter file as a fatal error #1703
Merge branch 'develop' into feature/job_src
Fix plugin JAR compilation classpath configuration
Run JUnit tests from Ant like in Maven
Add Ant libraries to Ivy dependencies

This allows running dita command directly after building JARs and
running the integration process, without needing to define an external
CLASSPATH system variable.
Move messages.xml to resources
Merge branch 'develop' into feature/job_src