Extend 'margin-before' / 'margin-after' configuration

[vaclavsvejcar]

⚠️ BREAKING CHANGE: This feature causes breaking change to the YAML configuration.

Checklist

• Implement the code
• Change documentation

In current version of Headroom, if margin (empty lines) around generated header is needed, one can use the margin-before and margin-after config properties. These allow to define margin between header and preceding/following code, but aren't applied when header is very first (or very last) thing in the source code. This can cause trouble for example when keeping blank line after header, which is last thing in the file, is required.

In order to make this more flexible, current two configuration options are dropped and replaced by following ones:

• margin-top-code - defines margin (in no. of empty lines) between generated header and code above it, but only IF header is NOT the first thing in file.
• margin-top-file - defines margin (in no. of empty lines) between generated header the very top of the file, but only IF header IS the first thing in file.
• margin-bottom-code - defines margin (in no. of empty lines) between generated header and code below it, but only IF header is NOT the last thing in file.
• margin-bottom-file - defines margin (in no. of empty lines) between generated header the very end of the file, but only IF header IS the last thing in file.

Examples

                                -- <<< 'margin-top-file' set to '1'
{- some header -}
                               -- <<< 'margin-bottom-code' set to '2'

someFunc :: String
someFunc = undefined

[vaclavsvejcar]

Implemented in master, will be released as par of the v0.4.0.0.