[WIP] Plan for Ver 2.0.0

[Alignof]

• Use From trait and remove Decode trait (Use From trait instead of Decode #29)
• Remove decode/inst_16, decode/inst_32 module. (It should be merged) (Remove decode/inst_16 and decode/inst_32 directories #32)
• Add a method that indicate if is a compressed instruction to Instruction.
• Support F, D, Q extensions.