Added dedicated Doxyfile for Travis CI and updated .travis.yml to use graphviz

.travis.yml

@@ -1,6 +1,11 @@
 language: c
 sudo: false
 
+addons:
+  apt:
+    packages:
+      - graphviz
+
 # Blacklist
 branches:
   except:
@@ -11,7 +16,7 @@ env:
      - PRETTYNAME="cI2C: Arduino Hardware I2C for AVR (in plain c)"
      - GH_REPO_NAME: cI2C
      - GH_REPO_REF: github.com/SMFSW/cI2C.git
-     - DOXYFILE: $TRAVIS_BUILD_DIR/Doxyfile
+     - DOXYFILE: $TRAVIS_BUILD_DIR/Doxyfile.auto
 
 before_install:
    - source <(curl -SLs https://raw.githubusercontent.com/SMFSW/travis-ci-arduino/master/install.sh)

Doxyfile

@@ -58,7 +58,7 @@ PROJECT_LOGO           =
 # entered, it will be relative to the location where doxygen was started. If
 # left blank the current directory will be used.
 
-OUTPUT_DIRECTORY       = 
+OUTPUT_DIRECTORY       = workdir/
 
 # If the CREATE_SUBDIRS tag is set to YES then doxygen will create 4096 sub-
 # directories (in 2 levels) under the output directory of each output format and
@@ -716,7 +716,7 @@ CITE_BIB_FILES         =
 # messages are off.
 # The default value is: NO.
 
-QUIET                  = YES
+QUIET                  = NO
 
 # The WARNINGS tag can be used to turn on/off the warning messages that are
 # generated to standard error (stderr) by doxygen. If WARNINGS is set to YES
@@ -770,7 +770,7 @@ WARN_FORMAT            = "$file:$line: $text"
 # messages should be written. If left blank the output is written to standard
 # error (stderr).
 
-WARN_LOGFILE           = 
+WARN_LOGFILE           = doxy.log
 
 #---------------------------------------------------------------------------
 # Configuration options related to the input files
@@ -1729,7 +1729,7 @@ LATEX_EXTRA_FILES      =
 # The default value is: YES.
 # This tag requires that the tag GENERATE_LATEX is set to YES.
 
-PDF_HYPERLINKS         = NO
+PDF_HYPERLINKS         = YES
 
 # If the USE_PDFLATEX tag is set to YES, doxygen will use pdflatex to generate
 # the PDF file directly from the LaTeX files. Set this option to YES, to get a