Some values defined in `Base/*` are not properly visible.

[ppolesiuk]

As originally pointed out by @fatmage, some values defined in Base/* files should not be directly included in Prelude, but wrapped around some module instead. For instance, Base/Int provides minValue and maxValue, but to access them, we have to import Base/Int directly, which is not intended for Base/* modules. A better solution would be to wrap these values around Int module defined in Prelude or other module included in Prelude. Same applies for some values defined in other Base/* modules.