Merge remote-tracking branch 'upstream/master' into functions

Author: rajithv

.travis.yml

@@ -18,6 +18,7 @@ rvm:
  - 2.0
  - 2.1
  - 2.2
+ - 2.3.0
 
 matrix:
   exclude:

appveyor.yml

@@ -33,7 +33,9 @@ install:
 
   - set /p commit=<symengine_version.txt
   - git clone https://github.com/symengine/symengine symengine-cpp
-  - cd symengine-cpp  
+  - cd symengine-cpp
+  - git config --add remote.origin.fetch '+refs/pull/*/head:refs/remotes/origin/pr/*'
+  - git fetch origin
   - git checkout %commit%
   - cmake -G "MSYS Makefiles" -DGMP_DIR=C:\gmp -DBUILD_TESTS=no -DBUILD_BENCHMARKS=no .
   - make

ext/symengine/ruby_basic.c

@@ -212,6 +212,7 @@ int insert_entries(VALUE key, VALUE val, VALUE input) {
 
     basic_free_stack(ckey);
     basic_free_stack(cval);
+    return ST_CONTINUE;
 }
 
 VALUE cbasic_subs(int argc, VALUE *argv, VALUE self) {

notebooks/differentiation_example.ipynb

@@ -90,7 +90,7 @@
    "source": [
     "x = SymEngine::Symbol.new('x')\n",
     "p = SymEngine::Symbol.new('p')\n",
-    "half = Rational('1/2')"
+    "half = 1.quo(2)"
    ]
   },
   {