Update tslint to the latest version 🚀

[greenkeeper]

Version 4.1.0 of tslint just got published.

Dependency	tslint
Current Version	4.0.2
Type	devDependency

The version 4.1.0 is not covered by your current version range.

Without accepting this pull request your project will work just like it did before. There might be a bunch of new features, fixes and perf improvements that the maintainers worked on for you though.

I recommend you look into these changes and try to get onto the latest version of tslint.
Given that you have a decent test suite, a passing build is a strong indicator that you can take advantage of these changes by merging the proposed change into your project. Otherwise this branch is a great starting point for you to work on the update.

---

Release Notes

v4.1.0

• [new-rule] prefer-const (#1801)
• [new-rule] strict-boolean-expressions (#1820)
• [new-rule] no-magic-numbers (#1799)
• [new-rule] import-blacklist (#1841)
• [new-rule] promise-functions-async (#1779)
• [new-rule] no-inferred-empty-object-type: a type must be specified when using a generic class/function/etc (#1821)
• [new-rule-option] allow-named-functions added to only-arrow-functions (#1857)
• [new-fixer] prefer-const (#1801)
• [new-fixer] quotemark (#1790)
• [new-formatter] code-frame formatter shows you the error in context (#1819)
• [enhancement] no-internal-module failures highlight less text (#1781)
• [enhancement] Avoid auto-fixing errors that would result in compilation errors for rules that use type-check (#1608)
• [rule-change] only-arrow-functions will allow functions with a this parameter (#1597)
• [bugfix] no-use-before-declare false positive on named import (#1620)
• [bugfix] prefer-for-of was showing false positive when the element is assigned (#1813)
• [bugfix] The command line argument type-check was swallowing the next argument (#1783)
• [bugfix] tslint:disable-line was re-enabling tslint:disable (#1634)
• [bugfix] adjacent-overload-signatures did not work for constructors (#1800)
• [bugfix] checkstyle formatter was reporting errors under one file (#1811)
• [bugfix] trailing-comma was applied to parameter lists (#1775)
• [api] CLI logic moved into API friendly class (#1688)

Not sure how things should work exactly?

There is a collection of frequently asked questions and of course you may always ask my humans.

---

Your Greenkeeper Bot 🌴