Update mods' simulation data from/in their respective repos

Updated:
 - 0ad
 - han_china
 - milleniumad

Please consult the changelogs of the above projects for specific changes
Start of refactoration of server-side code

* The aim is to be more intelligent about the files loaded
* Previously we loaded all .json and .xml templates we could find into php and iterated through looking for the templates we wanted
   - This had the problem of requiring a fair few special cases (palisade walls, fauna_sheep)
* Now we try to handle things slightly more intelligently, only loading templates if they are mentioned in already loaded templates
   - We start with the civs
   - Load starting units
   - Load the structures they can build
   - Load the units these structures can train that haven't already been loaded
   - Etc.

NOTE: This commit has problems with traversing mod dependancies. This will be fixed in a later commit
Continue with refactoring: Mod traversal fixes

* We should now traverse mods a little better than in the last commit
Support more than one sequential tech in a phase

* If TechB depended on techA, and both techs were in the same phase, then we had the system trying to use techA as a phase for techB
* This should resolve it, at least on the serverside
Change naming structure for units, structs & techs

* Previously, the names of
  - units & structures were stored `{"genericName": "...", "specificName": "..."}`
  - techs were stored `{"name": {"generic": "...", "specific": {"athen": "...", "hele": "..."}}}`
* Now all three are stored as:
  -  `{"name": {"generic": "...", "athen": "...", "hele": "..."}}`
  which should be a little easier to manage
* `"specific": "..."` only appears when there is only one specificName specified in the template/JSON
Use current civ instead of entities own when deriving lists

* This gets round problems with `merc_*` units being built at other civs' buildings
Small tweaks

* Should help simplify and improve comprehension of code
Add prod's 0ad_ancient_empires mod

* For comparison purposes to base 0AD
* Also updates millenniumad
Update mods' simulation data from their respective repos

Updated:
 - 0ad
 - 0ad_ancient_empires

Please see the mods' own changelogs for specific changes
Add new mods to choose from

 - "amazones-0ad"
    by:     Domenique van Gennip (dvangennip)
    source: https://github.com/dvangennip/amazones-0ad

 - "delenda est"
    by:     Justus Avramenko (wowgetoffyourcellphone)
    source: https://github.com/JustusAvramenko/delenda_est