OGR style: support more options for Pen and Brush (#4982, #4983)

- For pen, support 'p' (pattern), 'cap', 'j' (join) and 'dp' (perpendicular offset)
- For brush, support 'a' (angle), 's' (size), 'dx'='dy' (gap)
msOGRUpdateStyle(): split it in 4 subfunctions. No functional change
OGR style: handle multiple combined tool and support 'l' (priority level) (#4982, #4983)
update msautotest
add missing entries to label copies
wip retrying offsetted follow labels
refactor label follow to avoid gotos
working version of displaced follow labels after overlap rejection