Load metadata from file

[dponomarenko-firstorion]

I would like to propose to add one more metadata loading mechanism for libphonenumber cpp version , which would load metadata from protobuf binary file.

This functionality is desired by developers, as it eliminates the need to rebuild and release new libphonenumber version when only data update is required.

I am proposing to add compile-time switch to differentiate between data loading from binary array and data loading from protobuf binary file.

Also new public function “bool ReloadMetadata(const string& filepath) added to PhoneNumberUtil class intended to provide ability to reload metadata without restarting client application process. Here is what ReloadMetadata will do :

1. free the memory occupied by already loaded metadata
2. load new metadata into the memory
3. replace protobuf binary file with new one.

@kkeshava @katbohm

[katbohm]

Hi there!
Thank you for your pull request and contributing to the LibPhoneNumber library.
As for the proposed changes, I think the functionality might be useful. My main note is that I think the two binary *.dat files shouldn't be checked in, but rather generated by build rules.

[dponomarenko-firstorion]

Hello @katbohm @kkeshava and @tvislavski!
Thank you so much for responding to our Pull Request and for comments which helped us to improve this code change!
As requested, I removed two binary *.dat files from repo and made them generated by build rules.
Also I responded to all other comments,
please review our latest changes,
Thanks!

[drudquist]

Hello @katbohm @kkeshava and @tvislavski,

Is there anything else needed for this PR?