**resource.go/assets.go**
* renamed `resources.go` to `assets.go`
* added dark glyphs - located in assets.go -> assets/glyphs/dark/
* moved original glyphs - located in assets.go -> assets/glyph/light/
**glyphbanner.go**
* added option to make glyphs vertical and/or dark
**rpcg.go**
* Added a random portal code generator this function takes no args and returns a string
**README.md**
* Fixed some typos (probably more to be fixed)
* Added example of vertical portal banner
* Added list of options for banner creation
* Added example of ``nmslib.RndPortal()`` usage
**go.mod**
* updated go version to 1.16
