MNT: Update .mailmap to improve matches

Author: effigies

.mailmap

@@ -36,9 +36,11 @@ Caroline Froehlich <carol.frohlich@gmail.com>
 Christopher J. Markiewicz <effigies@gmail.com>
 Christopher J. Markiewicz <effigies@gmail.com> <markiewicz@stanford.edu>
 Christopher J. Markiewicz <effigies@gmail.com> <effigies@bu.edu>
+Christopher John Steele <steelec@gmail.com>
 Cindee Madison <cindee@berkeley.edu>
 Colin Buchanan <colinrbuchanan@gmail.com>
 Colin Buchanan <colinrbuchanan@gmail.com> <cbuchanan@cray4.(none)>
+Colin Buchanan <colinrbuchanan@gmail.com> <mankind@MacBook.local>
 Daniel Brenner <daniel.brenner@me.com>
 Daniel Clark <danieljclark87@gmail.com>
 Daniel Geisler <daniel.geisler@gmail.com>