[PATCH v2] riched20: implement ITextRange/ITextSelection Copy and Cut

[Damjan Jovanovic]

Try 2 is rebased against the latest changes.

Clipboard handling is unified with the previous code in editor.c.
Manual tests show trying to cut from a read-only field beeps when
using WM_CUT or Ctrl+X, but not when using these APIs.

Signed-off-by: Damjan Jovanovic 
---
 dlls/riched20/caret.c         |  2 +-
 dlls/riched20/editor.c        | 51 +++++++++++++++---------
 dlls/riched20/editor.h        |  3 +-
 dlls/riched20/richole.c       | 46 ++++++++++++++++++----
 dlls/riched20/tests/richole.c | 74 +++++++++++++++++++++++++++++++++++
 5 files changed, 148 insertions(+), 28 deletions(-)