Log Message:
Update to 5.3

Changelog:
Changes from 5.2 to 5.3
-----------------------

It is possible to enable character width support for Unicode 9 by
configuring with `--enable-unicode9'; this compiles in some additional
tables.  At some point this support may move into a module, in which
case the configure option will be changed to cause the module to be
permanently loaded.  This option is not useful unless your terminal also
supports Unicode 9.

The new word modifier ':P' computes the physical path of the argument.
It is different from the existing ':a' modifier which always resolves
'/before/here/../after' to '/before/after', and differs from the
existing ':A' modifier which resolves symlinks only after 'here/..' is
removed, even when /before/here is itself a symbolic link.  It is
recommended to review uses of ':A' and, if appropriate, convert them
to ':P' as soon as compatibility with 5.2 is no longer a requirement.

The output of "typeset -p" uses "export" commands or the \ 
"-g" option
for parameters that are not local to the current scope.  Previously,
all output was in the form of "typeset" commands, never using \ 
"-g".

vi-repeat-change can repeat user-defined widgets if the widget calls
zle -f vichange.

The parameter $registers now makes the contents of vi register buffers
available to user-defined widgets.

New vi-up-case and vi-down-case builtin widgets bound to gU/gu (or U/u
in visual mode) for doing case conversion.

A new select-word-match function provides vim-style text objects with
configurable word boundaries using the existing match-words-by-style
mechanism.

Support for the conditional expression [[ -v var ]] to test if a
variable is set for compatibility with other shells.

The print and printf builtins have a new option -v to assign the output
to a variable. This is for bash compatibility but with the additional
feature that, for an array, a separate element is used each time the
format is reused.

New x: syntax in completion match specifications make it possible to
disable match specifications hardcoded in completion functions.