Add translation support

[jonnydgreen]

Closes: #17

Changes

• Adds translation support by resolving the Dialogue Sequence processing
• Adds translation support for POT files
• Adds translation support for CSV files
  • Make this the default since it's generally the most used?
• Adds translation support setting
• Auto-detect translation support
• Implements button/modal for exporting translation files
• (Optional) add locale mode/view for basic translation editing/testing
  • Very keen to add this as an option because it fulfils the premise of Parley being easy to use
• Adds tests
• Add POT example
• Add CSV example
• Translation support documentation
  • Including pre-requisites such as gettext
• Add support for nodes within each NodeAst
• Add Parley translations (within each constant)
• Add support for exporting to CSV(/POT)
• Add support for importing via CSV/POT
• Add support for auto-detection of resources in the godot project locale pane
  • Upon save
  • Upon new file created
  • Upon import

[jonnydgreen]

This is now ready - however before merging, I will test this over the next couple of weeks as it is a big (but non-breaking!) change :)