function _copyArray(source, target) {
      for (var i = 0, l = source.length; i < l; i++) {
        target[i] = source[i];
      }
    }
#Description:
=====================================================
Generate random file name with extension

The argument provide extension type
-> raster
-> vector
-> 3d
-> document

If nothing is provided the function return random file name with random
extension type of any kind

The user can validate the file name length range
If nothing provided the generated file name is random

#Extension Pool :
* Currently the supported extensions are
 -> some of the most popular raster image extensions
 -> some of the most popular vector image extensions
 -> some of the most popular 3d image extensions
 -> some of the most popular document extensions

#Examples :
=====================================================

Return random file name with random extension. The file extension
is provided by a predefined collection of extensions. More about the extension
pool can be found in #Extension Pool section

chance.file()
=> dsfsdhjf.xml

In order to generate a file name with specific length, specify the
length property and integer value. The extension is going to be random

chance.file({length : 10})
=> asrtineqos.pdf

In order to generate file with extension from some of the predefined groups
of the extension pool just specify the extension pool category in fileType property

chance.file({fileType : 'raster'})
=> dshgssds.psd

You can provide specific extension for your files
chance.file({extension : 'html'})
=> djfsd.html

Or you could pass custom collection of extensions by array or by object
chance.file({extensions : [...]})
=> dhgsdsd.psd

chance.file({extensions : { key : [...], key : [...]}})
=> djsfksdjsd.xml

@param  [collection] options
@return [string]