Also prevent compiler complaining about inconistent dllimport/dllexport 
linkage by ensuring KM_KBP_EXPORTING is defined on Windows too.

Make it clear the $id needs to be changed.

Check context_items_to_utf16 doesn't overrun it's buffer.
Add tests for context_clear, context_shirnk and context_append.
Add test including marker type context item.

Need to correctly terminate the context_item presentation form array.
Also refactor the method onto the km_kbp_context adadaptor class where 
it belongs.

It can do allocation when prepending. Catch exception and turn into a 
status code.

Covers everything except appending and shrinking.

It did not read the input string due an error in 
utfcodec:_utf_sentinal_iterator and did not include the null terminator 
in calculated size from context_to_utf16.

Also fix up a number of types in fucntion names and the KM_API macros to 
mark functions as exportable.

The type was called km_knp_option_set but the functions we called 
km_kbp_options_set_*

Export of action items still todo.

These will be needed by the state_to_json API call.

Also pull trivial adaptors for keyboard an context into the internal 
data structres header files.