[Utilities] Remove .set field of CleverDict

[odow]

Closes #1326

This simplifies things by removing .set field. It also fixes an inference issue in keys.

The downside is that it breaks the iteration order for items in a CleverDict initialized with storage but not yet filled.

To be honest, I don't really understand the need for pre-initializing the CleverDict. I've left the option, but it now calls size hint instead of pre-allocating the space.

[blegat]

The downside is that it breaks the iteration order for items in a CleverDict initialized with storage but not yet filled.

Can you elaborate on that ? I don't understand the change of iteration order

[odow]

d = CleverDicts.CleverDict{Int,Float64}(hash, inverse_hash, 3)
d[4] = 0.25
d[2] = 1.5

used to iterate 2, 4 because it assumed there were three elements, then we added d[4], then set d[2]. That leaves 1 and 3 as undef.

Now preallocating with 3 will sizehint!(d.vector, 3), but not actually preallocate the storage.

[blegat]

Ok I see, the OrderedDict iterates by order of creation while the vector storage iterates by order 1:n. There order match if we only allow the vector storage to be filled in the order 1, 2, 3, ....
In your example, we were using the vector storage even if it wasn't filled in the right order. That makes the order of iteration not match the order of creation which wasn't great. I would say this changes is an improvement.

[odow]

I'll wait for @joaquimg to take a look before merging.

[joaquimg]

I am ok with removing the sizehint on init. People can do that in two steps.

[odow]

@joaquimg says we should just remove this argument.

[odow]

I'll remove the input argument in a separate PR.