Try to use gnuplot>=4.7 on Travis

.travis.yml

@@ -5,6 +5,7 @@ os:
   - osx
 julia:
   - 0.6
+  - nightly
 notifications:
   email: false
 git:
@@ -12,15 +13,16 @@ git:
 
 ## uncomment the following lines to allow failures on nightly julia
 ## (tests will run but not make your overall status red)
-#matrix:
-#  allow_failures:
-#  - julia: nightly
+matrix:
+  allow_failures:
+    - julia: nightly
 
 ## uncomment and modify the following lines to manually install system packages
 addons:
   apt: # apt-get for linux
     packages:
-    - gnuplot
+    - gnuplot>=4.7
+
 before_script: # homebrew for mac
   - if [ $TRAVIS_OS_NAME = osx ]; then brew install gnuplot; fi
 

src/GnuplotInternals.jl

@@ -122,7 +122,7 @@ function checkGnuplotVersion()
         end
     end
 
-    if ver < v"4.6"
+    if ver < v"4.7"
         error("gnuplot ver. >= 4.7 is required, but " * string(ver) * " was found.")
     end
     log(1, "Found gnuplot version: " * string(ver))