The problem seems to be the use of path variables in include dirs, we should resolve these (preferably before caching).

I'm reopening this, because it still doesn't work as it should.

If a file is in an "external include" directory, but also in another project that is open in the workspace, then the latter should be found, not the former.

This means we have to keep track of which include directories are inside the project (to check first) and which ones are externals (to check third, after the sibling projects). It would be nicer if there were two different properties, maybe in the future.

Updating tickets (#156, #550, #554, #649, #650, #606, #631, #755, #782, #783, #714, #747, #753, #688, #712, #723, #730, #732, #733, #734, #735, #740, #756, #757, #758, #763, #764, #765, #777, #787, #792, #689)

Updating tickets (#723, #730, #732, #733, #734, #735, #740, #753, #755, #756, #757, #764, #782, #787)