First draft for a travis-ci build script

Build logs are available at
  https://travis-ci.org/hmorlon/PANDA

The first build will fail because of a syntax error in test-fit-coal.r,
this is intentional and will be fixed in a later commit.
Add CRAN ppa to use R 3.0 instead of 2.14
travis: forgot to run apt-get update
travis: Also set R_LIBS

For unknown reasons, R_LIBS_USER seems to be ignored.
Try with setting R_LIBS instead.
travis: create $R_LIBS_USER directory, otherwise this variable is ignored

Remove R_LIBS, it did not solve anything.
Fix syntax errors in test-fit-coal.r
travis: introduce fake regression in test code

This is to show how errors are displayed on travis build logs,
and will be reverted once this commit has been built.
Revert "travis: introduce fake regression in test code"

This reverts commit 838dde23c912413e96399f396feffccd06b55b60.
fixed again pb with constant functions. WIP
still fixing Psi & Psi. WIP
still fixing Psi & Phi: applied to all subsections corrections
WIP