Support outline and labels resolved from main source file

[peterdell]

When working with includes, the outline and the label resolution only parse the file that are included into the current file via a source include directive. This has the effect that when editing an included file, the definitions of parent or brother files in the include tree are not visible. This is a major issue in larger projects with multiple include files.

The ideal solution would be to always start the parsing in the main source file, if specified in the include. The parsing should also take open documents in open editors into account. This will require to keep track of the different documents that are already opened. Also the user might want to select in the outline, if the displayed tree should started in the main source file or the current source file.

A minimal solution would be to tread the main source file annotation is source include directive and to only look into saved version of every file.

A simple workaround is to include the main source file in a block that is never assembled.