Add additional steps format and auto-highlights

[Gravifer]

This modification is a result from issue#34; the additional IntWithStepsOfTeXForm by @wuyudi and IntTraditional by @asdasd1dsadsa are integrated (with some change) as accepted values (resp., TeXForm and TraditionalForm) for the RubiPrintInformation option to the Steps function. The corresponding ::usage message is modified as well.

MakeBox formatting for Subst is added as suggested by @asdasd1dsadsa, with minor modification. SyntaxInformation is added for Int and Steps; this covers the pull-request#43.

[asdasd1dsadsa]

By the way, the IntTraditional has been improved as https://github.com/asdasd1dsadsa/RubiSteps

[Gravifer]

@asdasd1dsadsa Wow this is so neat!