Replaced lodash.merge with merge-options

[underoot]

Replaced lodash.merge with merge-options (based on two options recommended in deprecation notice of deep-assign library). Noticed, that lodash.merge added ~50KB of code, which significantly increase size of bundle without proper reason for that. Now situation with merge-options much better:

• lodash.merge 50.1KB
• merge-options 4.1 KB
• deep-assign 1.3 KB

[stepankuzmin]

Maybe we can even switch to Object.assign if we don't do a deep merge here, what do you think?

mapbox-gl-directions/src/reducers/index.js

Line 57 in 15d305d

return merge({}, state, action.options);

[underoot]

Maybe we can even switch to Object.assign if we don't do a deep merge here, what do you think?

I bet we do, i.e. for controls. We can brake backward compatibility, but I don't think that we should