Fix some depwarns and ambiguities

[timholy]

Fixes #20

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 70.27%. Comparing base (75f8eb9) to head (62de34b). Report is 6 commits behind head on master.

:exclamation: There is a different number of reports uploaded between BASE (75f8eb9) and HEAD (62de34b). Click for more details.

HEAD has 9 uploads less than BASE

Flag	BASE (75f8eb9)	HEAD (62de34b)
	12	3

Additional details and impacted files

@@             Coverage Diff             @@
##           master      #22       +/-   ##
===========================================
- Coverage   89.47%   70.27%   -19.21%     
===========================================
  Files           1        1               
  Lines          38       37        -1     
===========================================
- Hits           34       26        -8     
- Misses          4       11        +7     

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[timholy]

Will require https://github.com/JuliaArrays/OffsetArrays.jl/pull/255 to pass tests