Enable right-justified text

[dimo414]

Original report by Michael Diamond (Bitbucket: dimo414).

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Example syntax:

ansi().out("Message").rightJustify().out("[ ").color(GREEN).out("OK").out(" ]");

Should ouput (in an 80 column window):

Message                                                                   [ OK ]

This is a little tricky since both the left- and right-justified text can have complex formatting, but we want to avoid just replicating the same logic twice. Ideally also rightJustify() wouldn't just return an Ansi instance since the right-justified text will have limited functionality (shouldn't be able to call rightJustify() again, no cursor movement, etc.).

I'm also not certain whether this should live in Ansi or AnsiUtils. It feels a little complex for Ansi, but it would fit nicely with it's fluent interface.

One idea would be for rightJustify() to simply record the current buffer length and insert $COLUMNS - rightSide.length() spaces at that index before outputting.

[dimo414]

Original comment by Michael Diamond (Bitbucket: dimo414).

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Unfortunately $COLUMNS isn't available unless the user runs export COLUMNS, which isn't desirable. Some workarounds in https://stackoverflow.com/q/1286461/113632