column density texture doesn't resize with window

[agurvich]

this leads to pixelation of image if app is started in small window and window is made full screen.

it seems to only be an issue with the projection (thank you @ageller for the suggestion) and so it's probably that the texture buffer is initialized to the window size at app startup and never changes. Should (hopefully?) be an easy fix:

• create a function that will destroy + create the texture buffer
• call it at startup
• call it on window resize
  • if that doesn't work because performance or something just call it when the box is checked.