This commit tries to simply the change. Instead of separating an
`OutputComponent` and a `PredefinedStyle`, I have combined the two into
just `OutputComponent`.
To still have the styles work, I added an impl to `OutputComponent` with
a function `components` which returns the components related to the
specified component.
For a simple output component this is trivial, but for the predefined
styles this is a list of other components.
The evaluating of the command-line parameter simplified significantly,
making use of Claps `values_t!` macro to parse the supplied parameters
into a `Vec<OutputComponent>`. After that it is simply a task of
combining all supplied output components into one vector.
Important: this means that the styles are now additive, rather than one
of the predefined styles overruling other parameters supplied.
The `--style` parameter now accepts a comma-separated list of strings,
where every element defines either a single output component (`changes`,
`grid`, `header`, `numbers`) or a predefined style (`full`,
`line-numbers`, `plain`).
If available, bat picks the first predefined style in the user-supplied
style-list and ignores everything else. If no predefined style was
requested, the other parameters that are simple output components will
be used.
Examples:
--style changes,full,numbers
Will internally be reduced to only the predefined style `full`.
--style plain,full
Will internally be reduced to only the predefined style `plain`.
--style changes,numbers
Will not be reduced, because the list does not contain any predefined
styles.
(Note: if `grid` is requested but no other parameters, bat still creates
the left-most column with a width of `PANEL_WIDTH`. I didn't want to
introduce further logic in this PR that drops or adapts the width of the
left column.)
