smarter automatic detection of areas for generalization as footways, based on what is a border

[matkoniecz]

Currently detail removal works as follows:

• buffer footway
• buffer road

make intersection of this buggers a footway

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Maybe it would be smarter to

• detect all small ares
• areas bordering road and footway and not being very large -> turn into footways

[matkoniecz]

and this should end as "no access" (note map border on the right!)

[matkoniecz]

here likely to footway (note area:highway + generated symbolic steps_