This is currently just a warning in GHC HEAD, but ought to be fixed
nevertheless:

    Variable ‘m’ is implicitly quantified due to a context
    Use explicit forall syntax instead.
    This will become an error in GHC 7.12.

Signed-off-by: Austin Seipp <austin@well-typed.com>

Manual merge from git.haskell.org/packages/haskeline.git
Original patch by Edward Z. Yang <ezyang@mit.edu>

Manual merge from git.haskell.org/packages/haskeline.git
Original patch by Ian Lynagh

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

This removes the dependency on the utf8-string package (except for ghc<7.4.1).
A few minor encoding/decoding corner cases were also fixed.

A couple cases which are known to have triggered this are:
- Entering a long (>2^15) input line
- Tab-completing a folder containing many files, with completionPaging:False

Here "large" means an area of >2^15 cells, e.g., 200x200.
Original patch by fryguybob@gmail.com.

Although GHC provides similar functionality by default, it will
terminate the program the second time that ctrl-c is pressed.  In contrast,
wrapInterrupt will throw an exception on every ctrl-c, which is better
behavior for the types of programs that use haskeline.

This prevents warnings about the stdcall calling convention on Win64.
This patch was submitted by Ian Lynagh.

This patch is a modified version of one submitted 
by Paul van der Walt.
It adds a "haskeline_" prefix to all of Haskeline's
C symbol names.  This avoids clashing symbol names with other
packages that implement the same C functions.  
(In particular, it prevents a clash with vty on "mk_wcswidth".)

This change is in preparation for using ghc>=7.4's encodings.

GHC has provided ctrl-c handling since ghc-6.10.  So that functionality
is now redundant.

I think the regression occured when I fixed #106.

This makes the terminal-style versus file-style behaviors explicit.
Temporarily breaks the Windows backend.

Fix #106: group all keys into one Event (on POSIX), and thus ignore all input after an unrecognized key.

  Summary of changes:
   - Removed RankNTypes; added Rank2Types, UndecidableInstances
   - Revamped Command interface to be simpler and more monadic
   - Refactored key/command processing into new module RunCommand
   - Begin infrastructure for emacs/vi modes to have their own state.
   - Make Monad boilerplate a little simpler
   - TODO: The Windows build is broken.

Partial fix for #81: Use grapheme clusters to model the line state.  Currently only works with combining characters whose Unicode general category is NonSpacingMark.