remove redundencies in the Doxygen documentation.

* Removed '\x0f' from the IRC exporter until I understand why it was here.

* Fixed exporter headers to make Doxygen happy.

',_`""\        .---,    
                                           \   :-""``/`    |    
          Ahaha mais vieux porc !!          `;'     //`\   /    
                                            /   __     |   ('.  
                                           |_ ./O)\     \  `) \ 
                                          _/-.    `      `"`  |`
                                      .-=; `                  / 
                                     /o o \   ,_,           .   
                                     L._._;_.-'           .     
                                       `'-.`             '      
                                           `.         '         
                                             '-._. -'

Unicode characters are encountered.

in the PS exporter (vieux porc !).

* Got rid of static buffers; we now use cucul_free() to free exported
    buffers.
  * Fixed light background in the ANSI exporter by adding escape sequences for
    most terminal emulators.