add dispatch for dot between Symmetric and Hermitian

[araujoms]

Fixes #234

I've only added inner products when both arguments are Symmetric or Hermitian, for a total of 6 additional methods. I think if some user wants to take an inner product between a Symmetric or Hermitian and a general matrix they're just asking for trouble, and it's ok to leave them on their own.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6e6a854) 89.61% compared to head (9d065e8) 89.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #236      +/-   ##
==========================================
+ Coverage   89.61%   89.63%   +0.02%     
==========================================
  Files          23       23              
  Lines        2156     2152       -4     
==========================================
- Hits         1932     1929       -3     
+ Misses        224      223       -1     

Files	Coverage Δ
src/dispatch.jl	53.22% <100.00%> (-0.99%)	⬇️

... and 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[odow]

This seems reasonable, even if it just kicks the can a little down the road.

[blegat]

Could you add tests ? Maybe we could check for ambiguities like https://github.com/jump-dev/MathOptInterface.jl/blob/master/test/runtests.jl#L36 ?

[odow]

Could you add tests

👍

Maybe we could check for ambiguities

This should be a separate PR, and probably by me or you. I took a look once and got scared so I stopped. There are too many for @araujoms to deal with.

[araujoms]

I don't know how to do that anyway, so I'd be most grateful if you step up.