Fix: getDeepPropFromObj does not work

[anseki]

A following code in getDeepPropFromObj function in preprocess.js doesn't work:

  propPath.replace(/\[([^\]+?])\]/g, '.$1');

The .replace() method returns a replaced string, and it doesn't change a original string (i.e. propPath). The above code drops a replaced string.
The replaced string must be received:

  propPath = propPath.replace(/\[([^\]+?])\]/g, '.$1');

---

A current code doesn't catch the properties that is named 2 or more length when VAR[PROP] style is specified.
For example:

var src =
  'VAR.A: <!-- @echo VAR.A -->\n' +
  'VAR.B: <!-- @echo VAR.B -->\n' +
  'VAR.AA: <!-- @echo VAR.AA -->\n' +
  'VAR.BB: <!-- @echo VAR.BB -->\n' +
  'VAR[A]: <!-- @echo VAR[A] -->\n' +
  'VAR[B]: <!-- @echo VAR[B] -->\n' +
  'VAR[AA]: <!-- @echo VAR[AA] -->\n' +
  'VAR[BB]: <!-- @echo VAR[BB] -->\n'
  ;

console.log(
  require('preprocess').preprocess(src, {
    VAR: {
      A: 'var.a',
      B: 'var.b',
      AA: 'var.aa',
      BB: 'var.bb'
    }
  })
);

Result:

VAR.A: var.a
VAR.B: var.b
VAR.AA: var.aa
VAR.BB: var.bb
VAR[A]: var.a
VAR[B]: var.b
VAR[AA]: undefined
VAR[BB]: undefined

A regexp in current code:

/\[([^\]+?])\]/g

This matches one character, except ], +, and ?.
I think that +? should have been a pattern not literal:

/\[([^\]]+?)\]/g

And, [^\]] is unnecessary because ? works:

/\[(.+?)\]/g

Result by the above:

VAR.A: var.a
VAR.B: var.b
VAR.AA: var.aa
VAR.BB: var.bb
VAR[A]: var.a
VAR[B]: var.b
VAR[AA]: var.aa
VAR[BB]: var.bb

---

A current code doesn't discern a property name via VAR.PROP and VAR[PROP], and it splits also a property name of VAR[PROP].
For example:

var src =
  'VAR.A.B: <!-- @echo VAR.A.B -->\n' +
  'VAR[A.B]: <!-- @echo VAR[A.B] -->\n'
  ;

console.log(
  require('preprocess').preprocess(src, {
    VAR: {
      A: {B: 'var.a.b'},
      'A.B' : 'var[a.b]'
    }
  })
);

Result:

VAR.A.B: var.a.b
VAR[A.B]: var.a.b

This PR discerns those.
Result by fixed code:

VAR.A.B: var.a.b
VAR[A.B]: var[a.b]

This fixed code discerns also a name like VAR[AA].B[CC.DD][E] correctly.

[BendingBender]

Thank you for your PR. I've implemented it quick-and-dirty style and didn't test it. This was not meant to be part of officially documented functionality just yet.