[FEATURE] (issue10): provide format specific usage text

Let lisousi provide format specific usage text from libdatrwxx.

src/ts/lisousi/help_text.txt

@@ -11,7 +11,8 @@ infile       input file
                  the format selected by "-type"
 
 informational output:
--xhelp       print detailed information regarding file formats
+-xhelp[=type] print detailed information regarding file formats
+             if "type" is specified, just print text for file format "type"
 -listexperimental 
              list experimental and non-operational options
 -v           be verbose

src/ts/lisousi/lisousi.cc

@@ -59,11 +59,12 @@
  *                        reproduced by the current version
  *  - 12/05/2015   V1.12a provide updated documentation
  *  - 21/09/2015   V1.12b indicate fix by advancing version id
+ *  - 26/10/2015   V1.12c provide format specific usage text
  * 
  * ============================================================================
  */
 #define LISOUSI_VERSION \
-  "LISOUSI   V1.12b   line source simulation"
+  "LISOUSI   V1.12c   line source simulation"
 
 #include "lisousi.h"
 #include "wnintegration.h"
@@ -91,7 +92,7 @@ int main(int iargc, char* argv[])
     // 0: print help
     {"help",arg_no,"-"},
     // 1: output file format
-    {"xhelp",arg_no,"-"},
+    {"xhelp",arg_opt,"all"},
     // 2: generate debug output
     {"DEBUG",arg_no,"-"},
     // 3: verbose mode
@@ -209,7 +210,14 @@ int main(int iargc, char* argv[])
     cerr << usage_text_version << endl;
     cerr << usage_text << endl;
     cerr << endl;
-    datrw::online_help(cerr); 
+    if (cmdline.string_arg(1) == "all")
+    {
+      datrw::online_help(cerr); 
+    }
+    else
+    {
+      datrw::online_help(cmdline.string_arg(1), cerr); 
+    }
     exit(0);
   }
 

src/ts/lisousi/usage_text.txt

@@ -16,6 +16,6 @@ usage: lisousi [-v] [-o] [-type type] [-Type type]
                [-spatialdistance]
                outfile infile [t:T] [f:F] [infile [t:T] [f:F] ...]
    or: lisousi --help|-h
-   or: lisousi --xhelp
+   or: lisousi --xhelp[=type]
    or: lisousi --listexperimental
 # ----- END OF usage_text.txt -----