phreg.fit: Parametric proportional hazards regression
In goranbrostrom/eha2: Event History Analysis

This function is called by phreg, but it can also be directly called by a user.

1	phreg.fit(X, Y, dist, strata, offset, init, shape, control)

`X`	The design (covariate) matrix.
`Y`	A survival object, the response.
`dist`	Which baseline distribution?
`strata`	A stratum variable.
`offset`	Offset.
`init`	Initial regression parameter values.
`shape`	If positive, a fixed value of the shape parameter in the distribution. Otherwise, the shape is estimated.If positive, a fixed value of the shape parameter in the distribution. Otherwise, the shape is estimated.
`control`	Controls convergence and output.