MAINT: Correct odeint messages

[vermelha]

accordind to issue #4565 odeint is writing messages to standard output. Change to use warnings for messages.

[vermelha]

Well, it wasn't a good idea to change global settings indeed.
What I see is just a need to remove this line:

warnings.simplefilter('always')

In the original issue #4565 it was mentioned that 'There should also be an option to "silence" it.'
It seems that changing warnings filter to "ignore" state will silence them without the need to add a new parameter to odeint function. If it's OK I'll make a new commit.

[ev-br]

I think it's best to make a new commit and squash them into one, git rebase -i HEAD~1 and then force-push the result.

[vermelha]

Done

[ev-br]

Not sure whether printmessg parameter is useful, but that can be done separately, and a change to use warnings instead of plain prints looks good. Merging, thanks @vermelha!

[vermelha]

You are welcome! Thanks for help @ev-br!
I suppose I should delete the branch now...?

[rgommers]

You don't have to, but it's indeed a good idea. I usually delete all merged branches to prevent my own repo becoming too messy.

[rgommers]

@vermelha if you include closes gh-4565 in your commit message next time, the issue will be closed automatically when the PR gets merged. Doesn't matter that it wasn't done here, but it's handy.

[vermelha]

@rgommers, thanks for advices!