[doxygen] fix logo, title display and mainpage typos

doc/doxygen/Doxylocal

 # This file contains local changes to the doxygen configuration
 # please us '+=' to add file/directories to the lists
 
-PROJECT_NAME          = "*" # a hack to get a version number but no title (is in the logo already), also see css (under #projectname)
+PROJECT_NAME          = "DuMuX" # a hack to get a version number but no title (is in the logo already), also see css (under #projectname)
 PROJECT_BRIEF         = "DUNE for Multi-{Phase, Component, Scale, Physics, ...} flow and transport in porous media"
 PROJECT_LOGO          = @top_srcdir@/doc/logo/dumux_logo_small.png
 PROJECT_NUMBER        = @DUNE_MOD_VERSION@

doc/doxygen/customdoxygendumux.css

@@ -1184,7 +1184,7 @@ dl.section dd {
 {
 	font: 120% Tahoma, Arial,sans-serif;
 	margin: 0px;
-  padding-left: 13px;
+  padding-left: 55px;
   padding-bottom: 10px;
 }
 

doc/doxygen/mainpage.txt

@@ -4,11 +4,11 @@
  * \brief documentation for the doxygen main page
  */
 
-/** \mainpage DuMu<sup>x</sup> Documentation
+/** \mainpage DuMu<sup>X</sup> Documentation
 
 \section intro Introduction
 
-Welcome to the DuMu<sup>x</sup> documentation pages. This documentation has been
+Welcome to the DuMu<sup>X</sup> documentation pages. This documentation has been
 generated using <a href="http://www.doxygen.org/index.html">Doxygen</a>, a free source code documentation system for
 documenting C/C++ code.
 
@@ -23,6 +23,6 @@ An overview of all availabe parameters is given in \ref parameterlist.txt.
 
 \section features Features
 
-An overview of special features implemented in the DuMu<sup>x</sup>-test-problems is given in \ref featurelist.txt.
+An overview of special features implemented in the DuMu<sup>X</sup>-test-problems is given in \ref featurelist.txt.
 
 */