Connect classes for OMS and symbol

[clange]

A look into org.jomdoc.lang.math.om.OMS tells that JOMDoc does not yet relate symbol occurrences inside formulae to the OMDoc symbol elements that define them. I.e. that if I have a <symbol name="foo"/> in a theory "bar", that some method of an <OMS cd="bar" name="foo"/> object is able to return a Symbol object, if the <symbol/> can be located within the current set of documents (actually a similar problem as running the collector).

[anonymous]

Milestone M* - JOMDoc core deleted

[dmisev]

This can only be done after #16

[dmisev]

Ok, now it's possible to get the symbol with Symbol OMS.getSymbol(). I've added these convenience methods for resolving the references to most of the classes, like Ref, Imports, OMR, etc.