Release v0.3.0

• Update HCL code to allow element references.
  It allows to reference a previous element in the next one.
• Update README.
• Update example.
• Fix Calculation of Node X Position Relative to Max x For Evolution thanks @cwarden!

v0.2.0

• Add a changelog.
• Add option to print executable version: ./go-wardley -V or ./go-wardley --version.
• Update HCL parsing code to allow for optional values.
• Update HCL parsing to print user facing diagnostic errors.
• Add fsnotify file watches.
• Allow defining Map Details (size) in HCL.