Travis: Add a check for trailing whitespace before any actual compilation.

.travis-build.sh

@@ -3,6 +3,12 @@
 set -e
 set -x
 
+if grep -r '\s$' src *.yml *.txt *.md Doxyfile .gitignore .gitmodules .travis* dist/*.desktop \
+                 dist/*.svg dist/*.xml; then
+    echo Trailing whitespace found, aborting
+    exit 1
+fi
+
 #if OS is linux or is not set
 if [ "$TRAVIS_OS_NAME" = "linux" -o -z "$TRAVIS_OS_NAME" ]; then
     mkdir build && cd build