Line multi labeling improved

[manisandro]

Followup of PR #1338, adds support for multi-labeling polygon perimeters.

TBH b190546 is really one big hack, but after spending some time looking at the pal code, it looks like adding proper multi-labeling support there is not straight forward. So this seems the easiest solution. Comments welcome.

Referring to the "Merge connected lines to avoid duplicate labels" issue pointed out in #1338, is there an actual case where this is relevant when multi-labeling is enabled? Couldn't the merge connected lines setting just be ignored in this case?

[dakcarto]

@jef-n Should this (excepting typos) wait until 2.5 dev cycle?

[mhugent]

assigned to @dakcarto

[dakcarto]

@manisandro Can you rebase this against current master branch and force push, please?

http://hub.qgis.org/issues/10654 has been elevated to Blocker, so your fix here should be considered ASAP.

@mhugent or @jef-n any comments on whether this should NOT be pushed before 2.4 release, assuming it tests out OK when I review it?

[dakcarto]

@manisandro I will review this tonight, in anticipation of pushing to master.

[mhugent]

@dakcarto: ok for me to push before 2.4 release

[dakcarto]

@mhugent Thanks. I was delayed pushing this when testing it, due to tracking down several errors. They eventually ended up being missing parts of the initial multi-labeling for lines commits and a tricky one regarding an enum. Finally had a chance to test on several machines and committed here.