SystemMap should stack Entity-names when overlapping

[ghosta0815]

When there is overlapping text on the Systemmap, the text should stack or be distribute in a way that it is easily readable. My personal preferrance would be, that it only stacks vertically (+/-Y), without changing the horizontal (X) alignment.

Just some thoughts about the implementation:

• Currently the init function of IconCollection creates the texts and the DrawMe takes care of the text positions (only a readout of the position is required there)
• To implement stacking, there must be a logic implemented somewhere, that detects overlapping texts (collision detection?) and distributes them.
• This logic can not be implemented in the Init function of IconCollection as it is required to recalculate the textpositions, based on the entity-movement. --> Most likely the logic must be implemented in the DrawMe event of IconCollection.
• However, performance could be an issue, when a lot of entity names must be displayed (fighters/rockets/civilian ships) and their positions calculated.

[ghosta0815]

It seems like the code in EntityEvents uses a Dictionary of Lists of IconBases. This way each Entity can have multiple Items displayed, like a name, a orbit and a symbol and is only referenced by a single Guid. Doing it this way might be time-consuming, when operations over the Elements of the List-Items are necessary (like identifying all name-Icons and stacking them).

I will try doing an implementation with Dictionary<string, Dictionary <Guid, IconBase>> with the first Dictionary key being {"OrbitIcons", "TextIcons", "EntityIcons"} that can be extended later if other Icons become necessary;

[ghosta0815]

Done with #196 and #197