allow frame rate adjustments
hello, I was always annoyed at the choppyness of libvte-based terminals so I added options to tweak the ~40fps limit and improve smoothness by not making the terminal inactive if so desired. These default to the old behaviour so nothing should break. this might also improve the situation for #95
I see that merge requests are disabled for this repository, so I'm not sure where to submit my changes. you can check out my merge request on my fork for the code and further details, let me know if you're interested and how to proceed