Fix spelling errors and improve documentation.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@10759 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

fluid/fluid.cxx

@@ -1296,7 +1296,7 @@ public:
   Fl_Process() {_fpt= NULL;}
   ~Fl_Process() {if (_fpt) close();}
 
-  // FIXME: popen needs the utf8 equivalen fl_popen
+  // FIXME: popen needs the UTF-8 equivalent fl_popen
   FILE * popen	(const char *cmd, const char *mode="r");
   //not necessary here: FILE * fl_fopen	(const char *file, const char *mode="r");
   int  close();