contrib [DOC]: add notes to style guide

contrib/README.style-guide

@@ -2,7 +2,6 @@ this is <README.style-guide>
 ============================================================================
 A style guide for Fortran, C, and C++ coding conventions
 --------------------------------------------------------
-$Id: $
 ============================================================================
 A common coding style to be used in all source code improves readability and
 reduces the risk of error. Different packages in Seitosh follow different
@@ -15,6 +14,10 @@ General:
 - use indentation to mark loops and if-then-else clauses
 - use only 2 characters of whitespace per indentation level
 - NEVER use tab-characters for indentation
+- lines shouldn’t exceed a length of 79 characters
+  it’s not because we’re mainly using VT100 terminals while developing,
+  it's rather because the diffs look nicer on short lines, especially in
+  side-by-side mode.
 
 ----------------------------------------------------------------------------
 Denomination of variables, classes, etc. (C++):
@@ -25,6 +28,9 @@ Denomination of variables, classes, etc. (C++):
   if there are more than one typnames necessary than use the 
   typenames C1, C2, ...
 - class names start with a capital character
+  use CamelCase for class names
+- use snake_case for variables and functions
+- names of constants begin with c_
 
 ----------------------------------------------------------------------------
 Other C++ conventions:
@@ -38,6 +44,18 @@ Other C++ conventions:
   3. static member functions
   4. member data
 
+============================================================================
+Commandline options
+-------------------
+common commandline options should be:
+
+  --type          to specify input file type for programs which do not produce
+                  seismogram output data file
+  --itype         to specify input file type
+  --otype         to specify output file type
+  --verbose       to produce verbose terminal output
+  --overwrite     replace existing output file
+
 ============================================================================
 File names
 ----------