Implement Travis CI line ending checks

In our repository, we want:

* All text files to use only LF ('\n') as their line endings. Not CRLF
  ('\r\n')

* All text files to end with a newline (Newline at EOF).

So, ideally, we should have checks that automatically check for these
requirements in our repository.

However, we can't impose these checks on all developers, namely Windows
developers. They could be using either LF or CRLF (e.g. if the developer
activated Git's core.autocrlf configuration). Even if we did, we can't
guarantee that developers do not bypass these checks. As such, we have
to implement these checks on the Travis CI level instead.

The next question is how do we implement these checks. Checkstyle is
already helping us with that, but it is not completely effective as it
does not check *all* text files -- it only checks the source files which
are used for compilation.  This means that it does not check things like
resource files (CSS and FXML files), test data and documentation.

While we could probably teach it to check all files, we meet another
problem; Checkstyle does not know what a text file is. At best, we can
only give it a filter of file extensions to check.

On the other hand, Git knows the difference between text files and
binary files. As such, let's implement some shell scripts that will use
Git's facilities to implement our line ending checks on all text files.
These checks will be run on Travis CI, thus guaranteeing that master
will not have any more line ending problems.

These checks are implemented in POSIX shell scripts so that Travis CI
would not need to download any additional dependencies in order to run
them. Furthermore, developers running Linux or Macs can also run them
locally without downloading additional dependencies as well. Windows
devs would be unable to run them, but then again these line ending
checks are not useful to them because as mentioned above, Windows devs
may be using CRLF line endings anyway.

Author: pyokagan

.travis.yml

@@ -2,7 +2,11 @@ language: java
 matrix:
   include:
     - jdk: oraclejdk8
-script: travis_retry ./gradlew clean checkstyleMain checkstyleTest headless allTests coverage coveralls -i
+
+script: >-
+    ./config/travis/run-checks.sh &&
+    travis_retry ./gradlew clean checkstyleMain checkstyleTest headless allTests coverage coveralls -i
+
 before_install:
           - "export DISPLAY=:99.0"
           - "sh -e /etc/init.d/xvfb start"

config/travis/check-eof-newline.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+# Checks that all text files end with a newline.
+
+ret=0
+
+for filename in $(git grep --cached -I -l -e '' -- ':/'); do
+    if [ "$(tail -c 1 "./$filename")" != '' ]; then
+        line="$(wc -l "./$filename" | cut -d' ' -f1)"
+        echo "ERROR:$filename:$line: no newline at EOF."
+        ret=1
+    fi
+done
+
+exit $ret

config/travis/check-line-endings.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+# Checks for prohibited line endings.
+# Prohibited line endings: \r\n
+
+git grep --cached -I -n --no-color -P '\r$' -- ':/' |
+awk '
+    BEGIN {
+        FS = ":"
+        OFS = ":"
+        ret = 0
+    }
+    {
+        ret = 1
+        print "ERROR", $1, $2, " prohibited \\r\\n line ending, use \\n instead."
+    }
+    END {
+        exit ret
+    }
+'

config/travis/run-checks.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+# Runs all check-* scripts, and returns a non-zero exit code if any of them fail.
+
+dir=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd) &&
+ret=0 &&
+for checkscript in "$dir"/check-*; do
+    if ! "$checkscript"; then
+        ret=1
+    fi
+done
+exit $ret