Fixing uv importing:
  Working around maya limitations:
  - cannot rename, delete or copy UVs when MFnMesh is create from a MFnMeshData object
    (which is exactly what the AlembicNode does)
  - cannot change the "current" uv set

  If the primary uv set name is not "map1" like maya expects, create a new uv set instead of using "map1".
  As a matter of fact, a secondary uv set name may very be using that name.

  This means mostly 2 things:
  - If you have renamed "map1" to something else before exporting, you will get an additional empty "map1" uv set (as it cannot be deleted)
  - If the current uv set is not "map1", the imported mesh current uv set will differ from the original mesh

  I don't like it much but this is still better than loosing data.

  In such situation, an additional script could be use to fix that state
maya AbcExport: only set UV source name if necessary
added sample script that restore current uv set from alembic primary uv source name if necessary (sadly this can't be done within the plugin)
added maya AbcImport options UI