Improved support for detecting missing dependencies:

- Added libpaper-dev package checking.

- Previously, SDL_Pango's bug forced Tux Paint to include a customized
  version of SDL_Pango.h in its distribution, so we couldn't tell if
  SDL_Pango was installed in the system by including SDL_Pango.h.  We made
  a new workaround for SDL_Pango's bug that does not require Tux Paint to
  include SDL_Pango.h, so now we can check for SDL_Pango installation.

- Makefile now includes a check for gettext installation and will not
  fail when attempting to generate .mo files or install .mo files.  Instead,
  Makefile will now display a warning and skip the .mo file generation and
  installation steps.

Many thanks to Arunodai Vudem for the patches.

src/tuxpaint.c

@@ -339,7 +339,7 @@ extern WrapperData macosx;
 #error "---------------------------------------------------"
 #endif
 
-/*
+
 #ifndef NO_SDLPANGO
 
 #include "SDL_Pango.h"
@@ -352,7 +352,7 @@ extern WrapperData macosx;
 #endif
 
 #endif
-*/
+
 
 #ifndef NOSOUND
 #include "SDL_mixer.h"
@@ -919,6 +919,13 @@ magic_api *magic_api_struct; // Pointer to our internal functions; passed to sha
 
 #if !defined(WIN32) && !defined(__APPLE__) && !defined(__BEOS__)
 #include <paper.h>
+#if !defined(PAPER_H)
+#error "---------------------------------------------------"
+#error "If you installed libpaper from a package, be sure"
+#error "to get the development package, as well!"
+#error "(eg., 'libpaper-dev_1.1.21.deb')"
+#error "---------------------------------------------------"
+#endif
 static const char *printcommand = PRINTCOMMAND;
 static const char *altprintcommand = ALTPRINTCOMMAND;
 char *papersize = NULL;