fixed tests and codesniffer complaints

some streamlining for the aggregation classes

Have an abstract base class for aggregations to ensure proper
signatures, reuse more code from the table syntax

Manual code style adjustments

PHP code sniffer autofixes

Automatic coding style fixes

feat: add list aggregation

Implement the list aggregation known from the dokuwiki data plugin. This
feature is useful when an entire table would be to much boilerplate.
Usually one would select only

feat: add list aggregation

Implement the list aggregation known from the dokuwiki data plugin. This
feature is useful when an entire table would be to much boilerplate.
Usually one would select only a few columns.

Enable the option sepbyheader to behave analogous to the data plugin.

Report any options that are not valid for a list aggregation as error.
Show that error during the render phase of a page. That way the error is visible
always when the page is rendered, not only after the initial save when it is
parsed.

See #90 and see SPR-710

show more ...

fixed method signatures

initial wizard generated structure