Add country search by numeric code

[Envek]

This pull request extends #125 allowing not only access country's numeric code value but also allows to search countries by numeric code.

[Envek]

There is one difficulty: user may pass numeric code as an integer to Carmen::Country.coded. Currently Carmen will throw an exception (trying to downcase a number), but if we allow user to pass numbers, there will be another difficulty - user may pass number with leading zero and Ruby will assume that there is an octal number and search results will be incorrect.

I've wrote handling code, that will accept numbers, but also will issue a warning, discouraging passing numbers. You can see it here: https://github.com/Envek/carmen/compare/numeric_code_search...handle_integer_numeric_code_searches?expand=1

I'm dislikes it in common, so, not sure, whether include it in this pull request or not.

[jim]

I think it's probably best to have multiple methods that search by a specific field instead of one that tries to handle all of the cases.

Possibly, we should rename coded to alpha_coded and add a new numerically_coded (or numeric_coded) method to search by numeric string. We would need to preserve the current API by aliasing coded to alpha_coded for the near future.

As far as handling a user passing an octal number accidentally, I think it's fine to not handle that case. Sometimes it is nice to help users do the right thing, but I think it's OK to expect them to understand the various numeric syntaxes in Ruby.

[Envek]

So, I've added multiple methods that search by a specific field, but keep Country::coded to search by all (including numeric code). Also, I've written detailed description in README, with warning about numeric syntaxes in ruby.

[matsubo]

+1

[jim]

This looks good. I will merge this before I release the next version.

[ecbypi]

@cdainmiller Thoughts on this PR? I had some thoughts on this outlined in #170.

[ghost]

Thanks @ecbypi - I'll follow up in #170

[ghost]

@jim What should we do here? Still thinking this looks good for a release? I'm not sure, but maybe this is something we want to merge into a version-2.0 branch instead of master?

[Envek]

Wow, this PR is already two years old and still mergeable! @jim, what do you think about it now?

[jim]

I think I intended to merge this a while ago. Sorry for the delay, @Envek. It's a small change to the existing API, and as several uses will find this useful, that's a good enough reason for me.