Higher level apis

• automated npm release
• jasmine specs that runs in chrome (puppeteer)
• tslint
• spec/formatSpec.ts to test all supported formats
• new low level call() function that resolves with more information: stdout, stderr, exitCode
• extractInfo() return value typings
• interactive execution context sample
• high level apis support for built in images
• npm test now execute both node and browser tests
• new call() low level function that resolves with stdout, stderr, exitCode (solves #11)
• src/list contains enums for "convert list" values - auto-generated using scripts/generateImEnums.ts
• npm run bundle generate bundle files that can be imported as js estandard modules or UMD - magickApi.js is one of these. uses rollup tool
• apidocs using typedoc to generate markdown - published in /apidocs and linked in readme - see apidocs
• getPixelColor
• dependencies updated (most importantly gulp 4)