feat: add solidity-style sources compilation

[d1ll0n]

Description

Added ability to provide a sources object in place of a path in the filesystem. Sources object has file names as keys and file data as values.

Changes

src/parser.js

• added function for parsing from sources object
• changed exported functions to determine whether to use sources or file parsing function

src/parser.spec.js

• added parser tests for sources object

src/runtime.js

• added the ability to pass sources object with runtime

src/runtime.spec.js

• added runtime tests using sources object

Sorry for the messy commits.