X86: Major rework of how regop microops are generated.

X86: Major rework of how regop microops are generated.
The new implementation uses metaclass, and gives a lot more precise control
with a lot less verbosity. The flags/no flags reg/imm variants are all handled
by the same python class now which supplies a constructor to the right C++
class based on context.

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extra : convert_revision : 712e3ec6de7a5a038da083f79635fd7a687d56e5