TCP1_baseTypes converted to LEM

Notes:

TCP1_baseTypes.lem:

parametric types need type vars: type err 'a = ... (this is really a problem with HOL I think)

TLang list is list TLang; TLang option is option TLang; TLang err is err TLang

tlang_typing: various syntax changes

FIXME note overloading of < <= etc on time values

this defn:
  seq32_coerce (SEQ32 a n) = SEQ32 ARB n
uses ARB at arbitrary type; it is only used to map between unit types

really don't like type based disambiguation