Add keyword parameters and list-valued arguments to

Add keyword parameters and list-valued arguments to
instruction format functions in ISA description language.

Take advantage of these features to clean up memory
instruction definitions in Alpha.

arch/alpha/isa/decoder.isa:
arch/alpha/isa/mem.isa:
arch/alpha/isa/pal.isa:
    Take advantage of new keyword parameters to disambiguate
    instruction vs. memory-request flags, and to provide
    a default EA calculation for memory ops (since 99% of them
    are the same).
arch/isa_parser.py:
    Add two new features to instruction format functions:
    - Keyword parameters, a la Python.
    - List-valued arguments.

    Also export makeList() function to Python code blocks,
    as this is handy for dealing with flags.

--HG--
extra : convert_revision : 99bbbaa2e765230aa96b6a06ed193793325f9fb0