feed_fun: Probability of actively questing and then finding a host
In IxPopDyMod: Framework for Tick Population and Infection Modeling

Probability of actively questing and then finding a host

1	feed_fun(x, y, a, pref, q, tmin, tmax)

`x`	Predictor 1 in transitions table. Numeric vector indicating host density for each of the host species. Length should be equal to the number of host species.
`y`	Predictor 2 in transitions table. Numeric vector of length 1 indicating temperature.
`a`	Parameter `a` in parameters table.
`pref`	Parameters named `pref` in parameters table. Numeric vector of length equal to the number of host species. Values are the preference for ticks in a given transition for each host species.
`q`	Parameter `q` in parameters table. Used in Briere function.
`tmin`	Parameter `tmin` in parameters table. Indicates minimum temperature at which ticks actively quest.
`tmax`	Parameter `tmax` in parameters table. Indicates maximum temperature at which ticks actively quest.