Tui

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* tui init now tries to determine defaults for command, progname, description,
versionstr, docsfile and configfiles from the 'main', keyword argument. It
does this by importing it, so application programmers should make sure it
does not do anything nasty on import before using this functionality. But
then again, if you are in the habit of writing python code that does nasty
things on import your feet are probably already chock full of bullets
anyway so a couple more should not make any noticeable difference.
* General code cleanup to be more python coding style guide compliant.
* Exceptions no longer use .sMessage.
* Exceptions can now be instantiated either with multiple args which are used
to format a standard error message, or with a single custom error message.
Exceptions that only take one formatter arg instead use the message keyword
argument for this purpose.

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* Feature: tui.__init__() now accepts a main keyword argument, which if present will be used to
determine the location of .cfg and .docs files and for introspection of __version__.

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* Deprecated: The methods tui.makeposarg() and tui.appendposarg() no longer have the varnum parameter.

* Feature: New instantiantiation parameter for PositionalArgument: optional = False.
Optional Positional Arguments' .parse() methods can now return None if they are given
nothing to parse. This also affects tui.makeposarg().

* Feature: New instantiantiation parameter for PositionalArgument: recurring = False.
A Recurring Positional Argument's .parse() method will consume the rest (at least one)
of the args and returns a list of parsed values. The list will be length 0 if there is
nothing more to parse. This also affects tui.makeposarg().

* Feature: Setting recurring = True on Option instantiation will cause Option.value() to return a
list of values where the first item is the builtin default and any following items will be
the rest of the values in the order parsed. This is also reflected in the tui.makeoption()
method.

* Bugfix: A single '-' character on the command line can no longer be interpreted as an empty option
abbreviation block.

* Bugfix: Fixed typos in .addconfigfiledocs() strings. The section on Formatting and Nonformatting
Options now has a correct heading, and also option1 and option2 from the example are labled
correctly as formatting and nonformatting, respectively.

* Bugfix: Fixed typo in ._parseoptions() (before: sOption, after: oOption.name()). This used to
crash tui (throw uncatched UnboundLocalError) when the method encountered superfluous
occurences of non-recurring Options inside Option abbreviation blocks. Now,
OptionRecurrenceError(ParseError) will be thrown instead (easier to catch, more useful
error msg. It is in fact caught by .initprog() method, if used).

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* Bugfix: "[%(command)s]" is now the default section name in config files rather than "[%(progname)s]" .

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* Feature: tui.makeoption() now accepts the "recurring = False <bool>" keyword argument.

* Feature: Default Format presenter is now "repr" instead of "str".

* Bugfix: DocVars can now be used in OPTION, ARGUMENT and FILE blocks with the documented
results.

* Bugfix: TextBlockParser will no longer append a single space to SingleParagraph blocks
when a blank line (whitespace only) is encountered.

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* Convention: formats.Formats should no longer return None (reserved for unused optional positional arguments).
* Bugfix: Paragraphs split over multiple lines in docs files are now always
concatenated with exactly one separating space character