set mapping for proj:transform

[philvarner]

Related Issue(s):

• n/a

Proposed Changes:

1. For the first item indexed in a new collection, if all values in the
   proj:transform array were integers, the values were typed as integers,
   which would then cause an error for subsequent items that had float values
   in the array.

PR Checklist:

• I have added my changes to the CHANGELOG or a CHANGELOG entry is not required.

[ircwaves]

Good catch!