Laaxus Revision of AI 0.7.3

fix army removal bug
Small countries better manage their money

precise changelog :

• fix a bug where countries would greatly underestimate the cost per construction points when having under 50 construction points
• fix army spending estimation that would accumulate for a month and not reset every week, making the country downsize the armies
• Small countries will now accept a higher military spending before downsizing
• increased lroai_expected_ceiling_cost_per_construction_point to 1800
• decreased the estimated spending from investment pool
• allowed small countries to decrease their construction sectors 1 by 1, letting them not going into debt which leads to army downsizing
• various bugfix for bugs that appeared when fixing above mentionned bugs