Nyall Dawson ff3b4d5a74 Add API to set a label placement engine version, which dictates which
placement rules should be followed when solving the pal labeling engine
solution.

For new projects it defaults to version 2, but when loading an older project
version 1 is used.

This allows changes to be made to the label placement problem solving without
affecting the placement of labels in existing projects.
2019-11-28 09:54:51 +10:00
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2019-11-14 13:00:48 +10:00