Loading the last n Snapshots from LTM on Startup

Goal:

When starting a memory server the (last n) snapshots should be loaded from the long-term memory. This allows to recover more easily from crashes for example.

Steps:

• load all snapshots from LTM on startup of a memory server component using the export path and name, if component (e.g. Robot State Memory) calls the appropriate method
• add property to Memory (not LTM) that defines if reloading is triggered and if so trigger in Memory.cpp instead of single memory server components
• make amount of snapshots loaded a parameter
• make core segments to load a parameter
• make loading from another day possible
• call method from Plugin.cpp after connection was established, so the memory servers do not have to call it themselves

Tests:

• in Simulation, if snapshots can be loaded
• ARMAR-7, if snapshots can be loaded
• recovering localization data on startup ( @reister )