Uncaught TypeError: hexToRGB is not a function

This is from a fresh install of Pigments on the latest stable version of Atom. I'm not sure if it's related to this error, but nothing is being colored as well.

### Steps to Reproduce

1. Install atom-pigments
2. Run "Pigments: Reload", or change "Sass Shade And Tint Implementation" setting (to bourbon or compass)

**Atom**: 1.22.1 x64
**Electron**: 1.6.15
**OS**: Ubuntu 16.04.3
**Thrown From**: [pigments](https://github.com/abe33/atom-pigments) package 0.40.2

### Stack Trace

Uncaught TypeError: hexToRGB is not a function

```
At /home/steve/.atom/packages/pigments/lib/color.coffee:163

TypeError: hexToRGB is not a function
at Color.set (/packages/pigments/lib/color.coffee:163:31)
at /packages/pigments/lib/color-expressions.coffee:50:3)
at ColorExpression.module.exports.ColorExpression.parse (/packages/pigments/lib/color-expression.coffee:51:13)
at ColorParser.module.exports.ColorParser.parse (/packages/pigments/lib/color-parser.coffee:11:17)
at ColorContext.module.exports.ColorContext.readColor (/packages/pigments/lib/color-context.coffee:181:22)
at VariablesCollection.module.exports.VariablesCollection.evaluateVariableColor (/packages/pigments/lib/variables-collection.coffee:325:21)
at /packages/pigments/lib/variables-collection.coffee:253:10
at VariablesCollection.module.exports.VariablesCollection.evaluateVariables (/packages/pigments/lib/variables-collection.coffee:267:5)
at /packages/pigments/lib/color-project.coffee:98:18
at Function.module.exports.Emitter.simpleDispatch (/packages/pigments/node_modules/event-kit/lib/emitter.js:25:14)
at Emitter.module.exports.Emitter.emit (/packages/pigments/node_modules/event-kit/lib/emitter.js:141:28)
at /packages/pigments/lib/color-project.coffee:84:41
at /usr/share/atom/resources/app/src/config.js:676:22
at /usr/share/atom/resources/app/src/config.js:693:26
at Function.module.exports.Emitter.simpleDispatch (/usr/share/atom/resources/app/node_modules/event-kit/lib/emitter.js:25:20)
at Emitter.module.exports.Emitter.emit (/usr/share/atom/resources/app/node_modules/event-kit/lib/emitter.js:141:34)
at Config.module.exports.Config.emitChangeEvent (/usr/share/atom/resources/app/src/config.js:884:35)
at Config.module.exports.Config.setRawValue (/usr/share/atom/resources/app/src/config.js:670:25)
at Config.module.exports.Config.set (/usr/share/atom/resources/app/src/config.js:248:20)
at SettingsPanel.set (/usr/share/atom/resources/app/node_modules/settings-view/lib/settings-panel.js:237:27)
at HTMLSelectElement.changeHandler (/usr/share/atom/resources/app/node_modules/settings-view/lib/settings-panel.js:251:24)
```

### Commands

```
2x -8:25.6.0 settings-view:open (input.hidden-input)
3x -6:21.3.0 core:confirm (input.hidden-input)
-5:14.3.0 core:backspace (input.hidden-input)
2x -5:05.6.0 core:save (input.hidden-input)
-4:14 core:move-up (input.hidden-input)
-4:13.1.0 core:move-down (input.hidden-input)
-4:12.9.0 editor:move-to-end-of-screen-line (input.hidden-input)
-3:32.3.0 core:save (input.hidden-input)
-3:02.1.0 editor:delete-to-previous-word-boundary (input.hidden-input)
3x -3:00.8.0 core:save (input.hidden-input)
4x -1:54.4.0 core:backspace (input.hidden-input)
2x -1:53.6.0 editor:delete-to-previous-word-boundary (input.hidden-input)
-0:30.2.0 core:select-all (input.hidden-input)
-0:29.2.0 core:backspace (input.hidden-input)
```

### Non-Core Packages

```
atom-beautify 0.30.5
language-gitignore 0.3.0
language-haml 0.25.2
language-pug 0.0.21
language-vue 0.23.1
language-vue-component 0.5.0
markdown-preview-plus 2.4.16
minimap 4.29.7
pigments 0.40.2
pure-syntax 0.3.0
```

The error occurs in lib/color.coffee at line 163 where hexToRGB is called but not defined. Start by examining the color.coffee file to see if hexToRGB is imported or defined elsewhere. Check the surrounding code for missing function definitions or import statements. Run the package in Atom's developer mode to reproduce the error and verify the fix.

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