Updated todo
Un-inlined flag functions - it's worth loosing a couple of CPU cycles for the sake of cleaner code
Fixed bug where the window didn't redraw when the number of digits in the maximum line number changed
Moved helper functions for calculating the size of the line numbers from buffer to bufwin
Fixed a small bug in error handling
Found the exact issue in printing the VTE which, once fixed, meant the function to check if a character was allowed could be removed as it became implicit