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It turns out we can easily support breakpoints on expressions with
unlifted types, by translating 

  case tick# of _ -> e

into

  let f = \s . case tick# of _ -> e 
  in  f realWorld#

instead of just a plain let-binding.  This is the same trick that GHC
uses for abstracting join points of unlifted type.

In #2845, GHC has eta-expanded the tick expression, changing the
result type from IO a to (# State#, a #), which was the reason the
tick was suddenly being ignored.  By supporting ticks on unlifted
expressions we can make it work again, although some confusion might
arise because _result will no longer be available (it now has
unboxed-tuple type, so we can't bind it in the environment).  The
underlying problem here is that GHC does transformations like
eta-expanding the tick expressions, and there's nothing we can do to
prevent that.

Can't use windowed regs because the window moves during a function
call. Can't use the global regs because they're reserved for other purposes.

My previous patch didn't completely solve the problem.
I believe I got it right this time.

Fix a bug in :print affecting data types with unboxed components

  The x86 code generator sometimes generates nop moves like
  movl %vI_a %vI_a, but we'll just ignore them for coalescing
  purposes instead of emitting an error. It shouldn't hurt anything.

I forgot to record some additional changes.

Simon P-J suggested the following simplifications in #3097:

* Allow nested foralls in `ctype` just like in `ctypedoc`.
* Use `gentype` rather than `type` in the LHS of type declarations.
* Inline `type` in `ctype`.
* Rename `gentype` to `type`.

This patch does this. Also, the equivalent thing is done for documented types.

postEventTypeID was used to post event marker IDs, but instead we just
call postWord16 directly; thus, this function is unused.

For consistency, changed access of thread id to be through capability instead of directly from StgRegTable.

StgWord64 other better represents this argument since it can be used as
any particular data, thus "other" and not the "from" capability as it was
previously strictly used.  Also, StgWord64 is normally larger than type
nat to allow for larger data to be passed through the "other" argument.

Fixed ThreadID to be defined as StgThreadID, not StgWord64.  Changed CapabilityNum to CapNo.  Added helper functions postCapNo() and postThreadID().
ThreadID was StgWord64, but should have been StgThreadID, which is
currently StgWord32.  Changed name from CapabilityNum to CapNo to better
reflect naming in Capability struct where "no" is the capability number.
Modified EventLog.c to use the helper functions postCapNo() and
postThreadID () for CapNo and ThreadID.

EventTypeDescriptions order must be synchronized with the event type
definitions in includes/EventLogFormat.h for the definitions to correctly
index with the matching description.

This patch sligtly re-adjusts the way in which the syntax of types 
is handled:

 * In the lexer, '.' and '*' are always accepted in types
   (previously it was conditional).  This things can't mean
   anything else in H98, which is the only reason for doing things
   conditionally in the lexer.

 * As a result '.' in types is never treated as an operator.
   Instead, lacking a 'forall' keyword, it turns into a plain parse error.

 * Test for -XKindSignatures in the renamer when processing
     a) type variable bindings
     b) types with sigs (ty :: kind-sig)

 * Make -XKindSignatures be implied by -XTypeFamilies 
   Previously this was buried in the conditonal lexing of '*'

With the
    On x86, use thread-local storage instead of stealing a reg for gct
patch, on Windows and OS X:
    error: thread-local storage not supported for this target

One of these things is not like the others:

stdPattern :: [LRep] -> Maybe StgHalfWord
stdPattern reps
  = case reps of
        []  -> Just ARG_NONE    -- just void args, probably
        [N] -> Just ARG_N
        [P] -> Just ARG_N
        [F] -> Just ARG_F
        [D] -> Just ARG_D
        [L] -> Just ARG_L

Today's debugging session was brought to you by the letter P.

- Block concat and branch-chain elimination were allowing a function call
  to return to the caller's entry point. But that doesn't leave anywhere
  for the infotable on the stack, since the SP on return must be the same
  as the SP on entry to the procedure.

 - Previously, the node was taken as a parameter, then ignored,
   for static closures. Goofy. Now, the vestigial node parameters
   are gone.

Code simplifications due to call/return separation; some improvements to how node argument is managed

Benchmarks show that using TLS instead of stealing a register is
better by a few percent on x86, due to the lack of registers.

This only affects -threaded; without -threaded we're (now) using
static storage for the GC data.