Simulation templates: Allow XPath to reference another XML node's value.

[Radagast]

It would be nice to allow XPath references in simulation templates to avoid redundancy and to lessen the manually edited information that is hard to maintain.

e.g. consider the following:

 <?xml version="1.0" encoding="utf-8"?>
 <Entity parent="template_unit_cavalry_ranged_archer">
   <Identity>
     <Civ>chin</Civ>
     <Classes datatype="tokens">Ranged Cavalry Horse Archer Crossbow</Classes>
     <SelectionGroupName>units/chin_cavalry_crossbowman_b</SelectionGroupName>
     <GenericName>Chinese Mounted Crossbowman</GenericName>
     <SpecificName>?</SpecificName>
     <Icon>units/chin_cavalry_crossbowman.png</Icon>
     <Tooltip>Classes: {/Entity/Identity/Classes}.
         First occurrence: {first_occurrence}.
         Zenith: {zenith} 
         Last occurrence: {last_occurrence}.</Tooltip>
   </Identity>
   <Promotion>
     <Entity>units/chin_cavalry_crossbowman_a</Entity>
   </Promotion>
   <VisualActor>
     <Actor>units/china/cavalry_crossbowman_b.xml</Actor>
   </VisualActor>
 </Entity>

It would require us to parse for that pattern {}, then check if it's an XPath {/*}. If it's an XPath then we resolve the value if possible and replace the placeholder with this value.

Alternatively we can use {Classes} or {VisibleClasses} and replace those as we do for {Civ}.

We needed an easy way to add such replacements dynamically in the templates then and the only solution without extra tagging I figured is to use the XPath which is already there anyway.

[Imarok]

Move tickets to Simulation as UI & Simulation got some sub components.