Fit a simple model to data (alt)

Alternate version of fit_model using x and y min and max; 1: Linear model, 2: SSasymp model, 3: Power model, 4: Exponential model; a_fit, b_fit and c_fit are starting parameter values.

fit_model2(
  proj,
  type = 1,
  xmin = 0,
  xmax = 1,
  ymin = 0,
  ymax = 1,
  a_fit = 1,
  b_fit = 1,
  c_fit = 0
)