Fixed wrong width calculation for variation selectors combined with r…

…egular characters. Fixes #50

Clarifications and improvements in the package documentation.

Merge pull request #47 from junegunn/eastasian-ambiguous

Allow configuring the width of East Asian ambiguous width characters

Fixed wrong transition for Grapheme boundaries. Fixes #30

Added ReverseString().

Width is 2 for any characters ending with Variation Selector-16 (U+FE…

…0F).

Bugfix in StepString() function. Minor documentation improvements.

Merge pull request #26 from rivo/width

Monospace string width calculation (à la wcwidth).

Cleaning up latest actions and adding functions to detect trailing li…

…ne breaks.

Ignoring LB3 also in Step functions.