Created PM and Python rule to create AndLinks inside other link types

Specifically inside InheritanceLinks as this is necessary for the creation of links required for context rules
Added comments and explanations
Added separate rule to create AndLinks in 1st position
Created README for context example
Modified andlink inside link rules, added formulas
Merge pull request #904 from sebastianruder/context

Rule to create AndLinks inside other links (specifically InheritanceLinks) to be used with context rules