[Breaking API Change] Use list instead of set for filenames and contracts_names; change filename ordering

[montyly]

Build on top of #432 + merge dev + fix pylint

One thing I am unsure is if crytic_compile.filenames should return a list or a set. This is a merge of all the filenames from the different compilation units, so it can contain duplicate. Solutions:

• Return a Set
• Return a List where the duplicate are removed
• Return a List with duplicate

The set remove the order, however the order makes sense only at the compilation unit level, and not the CryticCompile level I think.

What do you all think?

[montyly]

(cc @samalws-tob for visibility)

[samalws-tob]

The reasons we need CompilationUnit.filenames to be ordered are:

• So that sourcemap numbers match file filenames indices
• So that the output is deterministic

Both of these apply to CryticCompile as well, so I think CryticCompile.filenames should be a list.

It seems like, in any case involving echidna, only one CompilationUnit per CryticCompile will be used. So I would say don't worry about the ordering of filenames in the case of multiple compilation units; feel free to remove duplicates or move things around or anything like that. All that matters is that in single-compilation-unit builds, CryticCompile.filenames is ordered in the same way as CompilationUnit.filenames.