Memoization

[jgersti]

• [x] cleanup Selector implementations
• [x] cleanup BlockHandler implementations
• [x] implement storage for caches (Cache)
• [x] cache block retrieval for block for block type + selector string per tick
• [x] cache block retrieval for block for block type + group name per tick
• [x] cache ITerminalActions
• [x] cache ITerminalPropertiess
• [ ] move BlockhandlerRegistry and caches into a seperate file?

[jgersti]

I did a quick test with the skid stering script. the avg runtime and instruction count is ~25% down.