Update Conan recipe

- Apply new conventions introduced on Conan 1.8
- Removed outdated settings
- Update license to follow SPDX format

Closes #926
Closes #943

.travis.yml

@@ -271,6 +271,19 @@ matrix:
               packages: ['clang-6.0', 'libstdc++-8-dev']
       env: COMPILER='clang++-6.0' CPP17=1 EXAMPLES=1 COVERAGE=1 EXTRAS=1
 
+    # 8/ Conan
+    - language: python
+      python:
+        - "3.7"
+      dist: xenial
+      install:
+        - pip install conan conan-package-tools
+      env:
+        - CONAN_GCC_VERSIONS=8
+        - CONAN_DOCKER_IMAGE=conanio/gcc8
+      script:
+        - python .conan/build.py
+
 install:
   - DEPS_DIR="${TRAVIS_BUILD_DIR}/deps"
   - mkdir -p ${DEPS_DIR} && cd ${DEPS_DIR}