fit_ma_gamma: Fit a MA-model with Gamma dfe
In dwinter/dfe: Distributions of Fitness Effects from new mutations

Fit a MA-model with Gamma dfe

1	fit_ma_gamma(obs, start = list(), fixed = list(), verbose = versbose, ...)

`obs,`	numeric observed fitnesses
`start`	a named list contaning starting values for any of the above paramaters Note, all paramaters must be given either a fixed or a starting value
`fixed`	a named list containing values for any of the above paramaters, that should be fixed during the maximum likelihood estimation
`shape`	numeric, shape parameter for Gamma
`rate`	numeric, Scale paramater for Gamma
`Ve`	numeric, envrionmental variance
`Ut`	numeric, expected number of mutations over the length of the