fix ctrl bug during reverse search
Merge pull request #14 from lirenlin/master

fix ctrl bug during reverse search
linenoiseSetCompletionCallback() now returns its prior callback, so that the caller can save/restore the value.
Merge pull request #15 from sgbeal/master

linenoiseSetCompletionCallback() now returns its prior callback, so that...
added API docs.
Merge branch 'msteveb_master'.
Added proper comments for my personal API functions.
Extended the linenoise API with a function returning the terminal height.