Optimize documentation plugin to work with subpages

[idelatorre]

• resolve issue regarding subpages links in Eclipse Help and PDF

[idelatorre]

Now the plugin works with more than one mediawiki file, a unique pdf file is created with all the files and the links work correctly in Eclipse Help and PDF but it is neccessary follow the Tips indicated in the documentation page https://github.com/openETCS/toolchain/wiki/Documentation#Generating_Documentation

The plugin has been upload to toolchain repository (https://github.com/openETCS/toolchain/tree/master/tool/bundles)

[jastram]

Thanks!