Have requirePackages check package versions

[larskotthoff]

This should be parsed from the description of the package (in particular suggests).

[berndbischl]

for suggests

[berndbischl]

@larskotthoff
what excactly did you want here? (i know this is really old)

[berndbischl]

ah. if we require a package internally, and in our DESC in SUGGESTS we have a minimal version, we should respect this.

without the user entering a manual min.version as an argument, as that is cumbersome and redundant