Remove useSpaceSeparators and only have per ast node configuration

[dsherret]

It would be better to remove the global useSpaceSeparators because I don't want certain behaviour by default.

For example, I like a space after an if keyword:

if (true) {}

But I don't like it after the function name:

function test () {
}

I also don't like it after the new keyword in constructor types and constructor function signatures:

new (...etc...)

useSpaceSeparators implies that there should be a space in both those cases.

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Instead of the above, leave it to just having per AST node configuration.

Relates to #164.

[lazarljubenovic]

The spaces preferences really divide people in endless categories! I like spaces before parenthesis in function/method declarations, but not in calls.

function foo () { }
foo()

So that's another case 🤔