#1145 Fix some EnvVars problems, one of them is a show stopper

[Miguel Gimenez]

The EnvVars plugin has some problems:
When you configure a project to use an envvar set, you get a "Set not found" error (show stopper)
Once the previous issue is fixed, If you change the set you must close and reopen the project for the change to be effective
When you edit a set in Preferences, only the changes to the visible set are saved; the rest are lost
There was a Unicode-related hack in EnvVarsDebugLog() and an unneeded overload with lots of duplicated code
* Set list is not sorted when shown

The attached patch fixes these, and also:
corrects coding style
adds const where applicable
take constant expressions out of the loops
some code refactoring for clarity
* removed the _T() macro where not needed

The coding style changes (specially tab size) make the patch difficult to review. I have attached a second patch without most the whitespace changes, this is intended for review only.

[bluehazzard]

Ok,
tested on windows and linux,
works fine for me,

Patch applied in r12537

Thank you a lot