Base code for Mem class and memory_blocks
Prototype of Ram class and Mblocks to gestionate RAM/ROM and Memmory mapped devices
Improve Address block managment
Polished some details. Checked that Read-Only blocks works as should be (like a ROM)
Merge pull request #1 from Zardoz89/ram_class

Ram class. Implemented a Address space block magnament. Allow to have Real ROM in address space, and memory mapped devices