Fixes the prefix trimming logic for package names and source files if
the source files appear in the package root (which is, unsurprisingly,
very common).
Due to the lexical walk order of `filepath.Walk` the previous
directory identification logic failed under certain conditions if the
top-level directory contained Go files that showed up *after* the
first subdirectories.
To simplify the logic a set of directories is now gathered instead on
a file-level.
Sub-packages of external dependencies are traversed by Nix as a tree
of attribute sets which need to be accessed by "path". To make this
easier, the dependency analyser now returns "paths" as string lists.
Adds a tool that can analyse dependencies that were not originally
meant to be built with buildGo.nix and return information that can be
used to construct appropriate Nix dependencies.
The tool will return information about package-local and foreign
dependencies separately to let Nix determine whether all required
dependencies are provided and to correctly link together sub-packages.
To avoid listing standard library imports in the dependencies, a list
of all packages in the standard library is generated statically to
allow for those to be filtered out during the analysis.
This tool is still work-in-progress.
