Update doxygen documentation

- Fix wrong paths to input (source) directories
- Add more information for developers

dev/doxygen/Doxyfile

@@ -665,8 +665,8 @@ WARN_LOGFILE           =
 # directories like "/usr/src/myproject". Separate the files or directories
 # with spaces.
 
-INPUT                  = ../../libs \
-                         ../../librepcb \
+INPUT                  = ../../libs/librepcb \
+                         ../../apps \
                          pages
 
 # This tag can be used to specify the character encoding of the source files

dev/doxygen/pages/code_style_guide.dox

@@ -19,6 +19,7 @@
             void foo() noexcept;            // this method never throws exceptions
             void bar() throw (Exception);   // this method can throw exceptions of type "Exception" (or any subclass of it)
             @endcode
+        - Use Qt's smart pointers @c QScopedPointer and @c QSharedPointer for object ownership (instead of raw pointers)
 
 
     @section doc_code_style_guide_header_files Header Files

dev/doxygen/pages/developers.dox

@@ -9,8 +9,10 @@
 
     @section doc_developers_git Git
 
-        - The "master" branch must always be compilable and executable. Bugs and non-finished features are allowed in this early development phase.
-        - Do not pack lot of changes in one commit. Make one commit per bugfix resp. one commit per new feature.
+        - The @c master branch must always be stable (CI successful).
+        - Use separate branches to fix bugs or implement new features.
+        - Do not pack lot of changes in one commit. Make small, incremental commits instead.
+        - Write commit messages according this guideline: http://chris.beams.io/posts/git-commit/
 
 
     @section doc_developers_internationalization Internationalization (i18n)