Scan less files for imports

[dtrunk90]

Example: main.less

@import "variables";
@import "core";

variables.less

@font-color: "black";

core.less

body {
    color: @font-color;
}

Now Eclipse complains about the variable used in core.less: The variable '@font-color' is undefined in this context.

This is theoretically correct, but practically wrong. Maybe scanning imported less files would fix it?

[DaSchTour]

Practically this is also correct, just the eclipse plugin doesn't recognize it!

[vtst]

This is the same as #147.