Trade adviser improved.
Empire goods price window add.
Fix exception when building gardens on edges of map.

If checked tile is on map edge there may be not enough space to upgrade garden. 'getFilledRectangle()' returns less tiles than needed but all of them may be valid garden, so we tried to upgrade - then exception was raised as some tiles were outside of map.
Filtering of walkers for overlays.

Some overlay display only subset of all walkers in city. Call setVisibleWalkers(array), where 'array' is list of walker types to display + WT_NONE at the end of array (so in extreme case it would be 'new WalkerType[] { WT_NONE }').
Helper function for drawing buildings in overlays. Example usage in food & water.
float properly handled
TradeOptions class improved. Window for trade options improved.
Àdd city trade options save\load. Add platform definitions in oc3_requirements.hpp.
Install instructions win/linux improved.
Trade routes add.
Merge branch 'fix/save-imigrant-speed' of https://github.com/nickers/opencaesar3
Empire Trade system improved.
Add merchants moving on trade routes.
Player city add to empire trade net.
Cart animations move to AnimationBank
City merchant class add.
Pictures load alg improved. Empire Trading system and city merchant improved.
Merge pull request #185 from dalerank/master

Get changes from dalerank
FileDir::getApplicationDir() implementation for OSX
Merge pull request #186 from veprbl/osx-patch

FileDir::getApplicationDir() implementation for OSX