This function uses testthat to test whether pre-requisites are met. It
first checks for availability of PsN via system_nm(), this is a requirement
for NMproject. Subsequent checks are not mandatory, but recommended for full
functionality - these comprise a check to see if NMTRAN checks are configured
and a check to see if code completion has been set up.
check_installation()Logical TRUE or FALSE indicating whether the tests have succeeded
or not. A test failure does not necessarily mean that NMproject
incorrectly configured. Test messages will say whether they are needed or
just recommended to pass.