Fixing a code generation bug

Fixing a big where minus-signs were being stripped from generated Go constants.

Thanks @mtratsiuk for reporting this.

Fixes to map handling with OpenAPI3

• Enables "allow-nulls" unit test suite for OpenAPI3
• Some bug fixes that prevented the tests from passing

OpenAPI 3 support

• Introduces OpenAPI3 support (with the -v3 flag)
• Maintains the original OpenAPI2 support
• Significant refactoring of the codebase:
  • Much more modular
  • Easier to test
  • More in line with GoLang project layout conventions
  • Switched to go mod (thanks for everything glide)
  • Removed globals

Map support (from Señor Skorodudemov)

Add map support (#11)

* Add map support

* Remove spew

Bug fixes from Kim Andre Hovelstuen Pettersen

minLength and maxLength weren't being properly marshaled by nytimes/openapi2proto, so we were unable to generate JSONSchemas containing these settings.

Kim has updated the unit test suite to pick this up (as well as using JSONeq), and for now this fix has been applied in our vendor folder.

Using latest openapi2proto, and added the "allow-nulls" option

0.1.0

New usage

Sorting the output for go-constants

Prior to this release the go-constants were unsorted, meaning that the schemas were potentially in a different order each time a go-constants file was generated (because they were fed from a map).

This release builds them in a slice instead, then sorts the schemas by their name before writing them out to files.

Supporting OpenAPI min/max field length attributes

• This version supports min/max field-length attributes (for string validation)
• The "official" (master) of NYTimes/Openapi2proto is vendored
• Unsafe (back-tick / "`" characters) are translated to single-quotes in description fields (because this was potentially breaking descriptions in generated go-constants, thanks to John Actual Daily)

Supports OpenAPI "pattern" attribute

This version supports the OpenAPI "pattern" attribute (defines a RegEx used to validate values).

Currently this depends on un-merged features in https://github.com/NYTimes/openapi2proto, so a modified version is vendored with this release.