[PHP MapScript] Add getStyle(), appendStyle() methods for classObj class

[dmorissette]

See bug 548.  Those new methods need to be ported to php_mapscript.

[dmorissette]

Pushing to 4.4 release

[assefa]

There were already functions in php mapscript that did similar things than the 
swig version describe in Bug 548 but not implemented in the same manner.

These functions are (on a class object):

     - styleObj getStyle(int index) 
     - int movestyleup(int index)
     - int movestyledown(int index)
     - int deletestyle(int index)

 There is also functions :
  - to create a style (default or base on anothe style) :   styleObj 
ms_newStyleObj(classObj class, styleobj style)
  - styleObj clone() : on a syle object


 I know that these are diffrent from the swig version, the main diffrence
being :
  * insertclass  defined (class0.insertStyle(new_style, 0) # insert at head of 
styles) is missing
  * the swig version used remove class instaed of deleteclass

 I am not willing to modify this for now since it can break applications. It 
should be considered in the future but not for this release.