Check if we haven't reached maximum memory when loading into databank

It can happen that there are so many strategies that they crash the program. 
We should check if there is at least 10% of free memory, and if not then don't create a new ResultsGroup or stop build process.


- In strategy loader before Resultsgroup is created - make a check, and if it fails throw an exception and don't load the strategy. Stop also loading other strategies if it is mass load.


- in Builder/Retester/Optimizer - check this everytime when strategy is saved into databank. If it fails don't add strategy and stop the project.


To get memory usage use: MemoryUsage.getMax(),getUsed()




Experiment with 10% boundary - if it is enough. Maybe it should be 15%, or some exact amount in MBs.