This patch implements Mirror influence for environment textures. Approach matches the one from BI. {F281871} See the video https://youtu.be/BskgCv6dcIE Example: {F281876} Alexander (Blend4Web Team) Reviewers: campbellbarton, merwin, brecht Reviewed By: brecht Subscribers: TwisterGE, blueprintrandom, youle, Evgeny_Rodygin, AlexKowel, yurikovelenov Differential Revision: https://developer.blender.org/D1786