add docker compilation to travis (#3433)

* add docker compilation to travis

add new matrix entry in .travis.yml for compiling on 18.04
add Dockerfile in .ci to build ubuntu 18.04 inside docker
remove release entry for uvuntu 16.04 to not conflict
refactor .travis.yml
refactor travis-comile.sh
merge travis-dependencies.sh into the travis.yml
remove travis-dependencies.sh

* enable debugging on travis-compile.sh

* set ubuntu16 buildtype to "Debug"

set buildtype Debug for as requirement for "test"
add --debug and --release flags to travis-compile.sh

* make output prettier

edit the format warning message and clangify.sh output

* fix clangify.sh

fix --cf-version flag
fix directory argument parsing
add directory parsing details to --help
add examples to --help

clangify.sh

@@ -4,13 +4,8 @@
 # Never, ever, should this recieve a path with a newline in it. Don't bother proofing it for that.
 
 
-# use script dir and return on exit
-current=$PWD
-function cleanup {
-  cd $current
-}
-trap cleanup EXIT
-cd "${BASH_SOURCE%/*}/"
+# go to the project root directory, this file should be located in the project root directory
+cd "${BASH_SOURCE%/*}/" || exit 2 # could not find path, this could happen with special links etc.
 
 # defaults
 include=("common" \
@@ -44,14 +39,19 @@ while [[ $@ ]]; do
       ;;
     '-h'|'--help')
       cat <<EOM
-A bash script to format your code using clang-format.
-If no options are given, all dirty files are edited in place.
-If <dir>s are given, all source files in those directories are checked, recursively.
+A bash script to automatically format your code using clang-format.
 
-USAGE: $0 [option] [-b[ranch] <git branch or object>] [<dir> ...]
+If no options are given, all dirty source files are edited in place.
+If <dir>s are given, all source files in those directories of the project root
+path are formatted. To only format changed files in these directories use the
+--branch option in combination. <dir> has to be a path relative to the project
+root path or a full path inside $PWD.
+. can not be specified as a dir, if you really want to format everything use */.
+
+USAGE: $0 [option] [--branch <git branch or object>] [<dir> ...]
 
 DEFAULTS:
-Default includes are:
+Current includes are:
   ${include[@]/%/
  }
 Default excludes are:
@@ -62,7 +62,8 @@ OPTIONS:
         Compare to this git branch and format only files that differ.
         If unspecified it defaults to origin/master.
         To not compare to a branch this has to be explicitly set to "".
-        When not comparing to a branch git will not be used at all and all valid files will be parsed.
+        When not comparing to a branch, git will not be used at all and every
+        source file in the entire project will be parsed.
 
     -c, --color-diff
         Display a colored diff. Implies --diff.
@@ -80,11 +81,23 @@ OPTIONS:
     -t, --test
         Do not edit files in place. Set exit code to 1 if changes are required.
 
+    --cf-version
+        Print the version of clang-format being used before continuing.
+
 EXIT CODES:
     0 on a successful format or if no files require formatting.
     1 if a file requires formatting.
     2 if given incorrect arguments.
     3 if clang-format could not be found.
+
+EXAMPLES:
+    $0 --test \$PWD || echo "code requires formatting"
+        Tests if the source files in the current directory are correctly
+        formatted and prints an error message if formatting is required.
+
+    $0 --branch $USER/patch-2 ${include[0]}
+        Formats all changed files compared to the git branch "$USER/patch-2"
+        in the directory ${include[0]}.
 EOM
       exit 0
       ;;
@@ -96,24 +109,31 @@ EOM
       mode=code
       shift
       ;;
+    '--cf-version')
+      print_version=1
+      shift
+      ;;
     '--')
       shift
       ;;
     *)
-      include=() # empty includes
-      while [[ $@ ]]; do
-        if [[ -d $1 ]]; then
-          include+=("$1")
-          shift
-        else
-          echo "error in parsing arguments of $0: $1 is not a directory" >&2
+      if next_dir=$(cd "$1" && pwd); then
+        if [[ ${next_dir#$PWD/} == /* ]]; then
+          echo "error in parsing arguments of $0: $next_dir is not in $PWD" >&2
           exit 2 # input error
+        elif ! [[ $set_include ]]; then
+          include=() # remove default includes
+          set_include=1
         fi
-      done
+        include+=("${next_dir#$PWD/}")
+      else
+        echo "error in parsing arguments of $0: $PWD/$1 is not a directory" >&2
+        exit 2 # input error
+      fi
       if ! [[ $set_branch ]]; then
         unset branch # unset branch if not set explicitly
       fi
-      break
+      shift
       ;;
   esac
 done
@@ -152,6 +172,9 @@ if ! [[ $names ]]; then
   exit 0 # nothing to format means format is successful!
 fi
 
+# optionally print version
+[[ $print_version ]] && $cf_cmd -version
+
 # format
 case $mode in
   diff)