English spelling corrections for /addons/
Various fixes and misspellings corrected.
addon > add-on
analyzer > analyser
color > colour
customizability > customisability
favorite > favourite
useage > usage
visualization > visualisation
visualizer > visualiser
Merge pull request #3309 from readmanr/english-check

English spelling corrections for /addons/
[EPG] Don't perform updates during video playback.

Lag and stutter may ensue.
[PVR] Detect framerate changes.