Support meta_merge in mymeta files #45

[Leont]

This should add support for merging in the prereqs part of meta_merge when generating MYMETA files.

This is a draft because it's lacking tests.

[haarg]

This seems to be assuming that meta_merge is in meta v2 format. Other parts of the code look like they are assuming they are v1.4. Or possibly making the assumption that a prereqs key would be meta v2 data would work well enough.

[Leont]

This seems to be assuming that meta_merge is in meta v2 format. Other parts of the code look like they are assuming they are v1.4. Or possibly making the assumption that a prereqs key would be meta v2 data would work well enough.

Fair, I should just upconvert if it isn't v2.