remove need for method source location

[grosser]

see #167

[zdrve]

I don't quite understand these two issues. They seem to be in conflict with each other.

Is this issue #170 saying that we should no longer attempt to report which source code line a value came from? That makes #167 redundant if so.

[grosser]

this is a placeholder issue to get the PR merged/resolved
... I guess I can just close it since we have the PR

the general idea was to remove source_location in favor of capturing the caller when defining the project so we only have 1 way of dealing with source locations