Normalize vim plugins

[matthewbauer]

We have a couple of Vim plugins in Nixpkgs that are not being normalized by Repology correctly:

https://repology.org/metapackages/?search=vimplugin&maintainer=&category=&inrepo=nix_unstable&notinrepo=&repos=1&families=&repos_newest=&families_newest=

I'm not sure what the correct way to normalize them is, but most are just named "vim-" instead of "vimplugin-" (see vim-pathogen vs vimpliugin-vim-pathogen).

[AMDmi3]

Vim plugins are not normalized by repology at all. Given the discrepancy:

https://repology.org/metapackages/?search=nerdtree

they will have to be merged by hand. Patches welcome.