Javascript arguments

[LFDM]

Splitjoins javascript function arguments.

Implementation is simply done by extracting and reusing functions already present inside js.vim. It might be even more generalizable by moving these helper functions to the main sj helper 'module', but this decision I would leave to you, @AndrewRadev.

Also fixes minor issues with semicolon handling in javascript. Splitjoining functions were producing js that wouldn't make it through a linter like jshint.

Note that this currently sits on top of #58 and should not be merged. Depending on the fate of #58 I would rebase or cherry-pick this accordingly before taking further action.

Closes #53

[AndrewRadev]

Looks good to me. I did something similar for python lists/tuples, and I left the helpers as script-local functions.

I don't indent to extract them, since there are some javascript-specific things, particularly indentation. I'd say this is good enough as it is.

Thanks for your work :).

[AndrewRadev]

I've had to make some changes to javascript if-clause handling due to issue #67.

Long story, short, I now have a branch called if-clauses-with-curly braces in which I've overwritten the javascript if-clause handling with the PHP one (since I wanted to unify them and I had to pick one and this one was implemented by me :P). This may mean that I've made mistakes in the implementation and I'd appreciate it if you could take a look (either at the implementation, or just try it out and see if it seems to work alright).

Also note that there's a variable now, g:splitjoin_javascript_if_clause_curly_braces, which controls whether curly braces are added or not upon splitting/joining. Its value is not a boolean flag as usual, but I've documented it, so I hope it's understandable how it works. Otherwise, do let me know :).