Merge in CGD/gather-and-defend from prog/population to main
* commit '6778880d5fed0d60c92f48995e62eca289bfaec3':
reset resources for real each level loading
oops forgot some staging
population mechanic with art
- added art for house and UI
- put population in ResourceManager
- create house prefab
- added code for adding and removing pop depending on entity
- refactor harvesters so they inherit from ally
- modify placeholders and buttons so that only units cost population
- add events for population and resources changing
- add population relative configs to global config
- add start resources values to Levels
- add debug feature for generating resources for free
