Clean compilation warnings

[mloskot]

It looks like this is going to be N-iterations task (intentionally marked as defect).

It's reasonable to clean as much compilation warnings as possible:

• The warnings thrown during compilation of projections module need to be fixed in the program generating it from  PROJ.4 (and other?) sources.

• Recommended way to remove unused variable warnings is to use  boost::ignore_unused_variable_warning. Do NOT use define or use any macros for this purpose. Example of correct fix:

  #include <boost/concept_check.hpp>
  
  void foo(int a)
  {
       boost::ignore_unused_variable_warning(a);
  }
  

It's been discussed  here and  there.

[mloskot]

Silenced few unused variables (r825)