add travis support

.Rbuildignore

@@ -1,2 +1,3 @@
+^\.travis\.yml$
 ^.*\.Rproj$
 ^\.Rproj\.user$

.travis.yml

@@ -0,0 +1,42 @@
+# Sample .travis.yml for R projects from https://github.com/craigcitro/r-travis
+
+language: r
+
+# sudo: required
+
+r:
+  - release
+  - devel
+
+warnings_are_errors: false
+
+cran: http://cran.at.r-project.org
+
+cache: packages
+
+r_packages:
+  - devtools
+
+r_github_packages:
+  - jimhester/covr
+
+after_success:
+  - Rscript -e 'library(covr);coveralls();codecov()'
+
+notifications:
+  email:
+    on_success: change
+    on_failure: always
+
+env:
+  global:
+    - NOT_CRAN: true
+    - R_CHECK_ARGS="--as-cran --timings"
+    - R_CHECK_TIME="TRUE"
+    - R_CHECK_TESTS="TRUE"
+    - _R_CHECK_TIMINGS_="0"  
+
+
+before_script:
+  - sudo apt install seq-gen
+