A module for loading a style processor
@module loadProcessor
 
Loads a module in 3 Steps.
1. Check if module is compatible
1. Check if module is installed
2. Check if module version is compatible
3. Load the module

@private
@param {String} moduleName
@returns {Promise} processor
function _loadModule(moduleName) {
	let modulePath
	// Check if module exists
	try {
		modulePath = require.resolve(moduleName)
	} catch (err) {
		switch (err.code) {
		case 'MODULE_NOT_FOUND':
			const error = new Error(`Processor ${moduleName} not found. Please install it first (npm install ${moduleName} --save-dev)`)
			error.code = 'MODULE_NOT_INSTALLED'
			throw error
		default:
			throw err
		}
	}

	//Check if module version is supported
	const f = finder(modulePath)
	const moduleVersion = f.next().value.version
	const compatibleVersion = compatibleProcessors[moduleName]

	if(!semver.satisfies(moduleVersion, compatibleVersion)) {
		const error = new Error(`Processor ${moduleName} (${moduleVersion}) is not compatible. Required version: ${compatibleVersion}`)
		error.code = 'MODULE_NOT_COMPATIBLE'
		throw error
	}

	return require(moduleName)
}