Update writeObjectsSections to match current Xcode format

[fbartho]

We've been noticing some thrash where a blank line gets deleted or re-added when adding new NativeModules to our react-native project.

Under the hood, several of our tools are using this npm package. After some experiments, I was able to figure out that current Xcode versions will automatically insert an extra blank line after the objects = { section of the Xcode project.

Looking at the source-code of this tool, I found that 7 years ago this was an intentional feature:

cordova-node-xcode/lib/pbxWriter.js

Lines 185 to 189 in 4159249

	if (!first) {
	this.writeFlush("\n")
	} else {
	first = false;
	}

With the current release version of Xcode, and indeed several previous versions of Xcode 10 and possibly later versions of Xcode 9, when Xcode writes out the project.pbxproj file, it will insert this blank line.

This PR brings cordova-node-xcode into line with that style.
Tested on Xcode Version 10.1 (10B61)

Aside: 15 of the 19 project fixtures had the old-style, while 4 of the fixtures had the new style, so either we have some unused fixtures, or some fixtures aren't using the pbxWriter for what they're testing?

[brodycj]

We've been noticing some thrash where a blank line gets deleted or re-added when adding new NativeModules to our react-native project.

Any pointers how I could reproduce this behavior on Cordova or React Native?

P.S. My Xcode shows the following version: Version 10.1 (10B61)

[fbartho]

Any pointers how I could reproduce this behavior on Cordova or React Native?

Absolutely! In my project it was reproducible by editing the file name of any file or group using Xcode. That would force Xcode to rewrite the pbxproj, and that adds in the blank line! (So, modify a project using node-Xcode, and then cause Xcode to modify itself, and compare both versions; Or, take an Xcode generated project, and then force node-Xcode to rewrite it, even though you changed nothing)

[fbartho]

Changes to the release notes are removed!

[brodycj]

Thanks @fbartho.

[brodycj]

Travis CI build is now green, merging now. I think this change should be considered a MINOR change as opposed to a "patch fix".