Do not remove a residual edge between A and B if there isn't another path
going between A and B. We previously would remove it if A and B had a common
ancestor, but that caused some value duplication as A could become a leaf
but its value would still be accounted for in B.

When reconciling samples, cleanup file paths to allow functions to be
combined if their source filenames match after cleanup (eg "src.cpp" and
"./src.cpp").

Also clean up existing uses of filepath to avoid passing empty strings
to it: filepath.Base("") returns "."

Also update the build instructions to use go get