'v1.3'

V1.2

1. Added developer documentaion dev_doc.md
2. there was one function that plots both velocity and xy before. So to adhere to standard I separated it into 2 functions, plot_ue and plot_xy. (previously it was plot_ue only). 
3. Few minor changes to show the logs correctly -- ex in file view tab and open a file, in the previous version the file_view does not get updated immediately if one opens a new file in that tab.
4. I was able to clear/remove ~10-20 lines of code as well
5. Added menu items for XFoil and xy format dat files
6. Works with Matplotlib > 3.4 -- Current Matplotlib is 3.8 and this will ease the first time installation because no need to install old version anymore