Make hook_update_N for new config key

OK, would you agree with the following logic: When changing the config key home_as_site_name (boolean in 1.9) to config key front_title (integer in 1.10):

• if home_as_site_name was FALSE, set front_title = 1 (Use the site name from the configuration settings)
• if home_as_site_name was TRUE, set front_title = 0 (Use "Home" as title)

You're right: as the code is now, the default value 0 for front_title when version 1.10 is installed will 'Use "Home" as title' regardless of how home_as_site_name was set in previous module versions. Let me know if you agree, confirm I haven't missed anything, and I'll write the update hook to push it out in version 1.11 ASAP.

@Grimreaper then I would also like to consider this a mentorship opportunity, since I'm pretty sure I could execute the logic for the variable settings but I don't know the Drupal standard way of checking the configuration relative to the version number. This is the first time an update hook has been required for this module & I want to be sure it's done right. So I would like to see the solution you have imagined & then will fast track that patch into a new version... what do you think?

I see what you mean about the testing: I tried to get it to run menu_breadcrumb.install when switching from the 1.9 module config & code to the 1.10 config & code, but couldn't make it work... i.e. I couldn't set up a test for how the upgrade would affect the config data without uninstalling the module & wiping out that config data.

However your code looks complete & accurate to me. Therefore maybe can leave this in dev for a couple of days until some more people have a chance to look at it? I'll push out as 1.11 first thing on Tuesday if no problems & thanks for the support.