Env had a very old way of reading environment variables from
before Java supported environemnt variables from System. This
commit makes the code the same as core CDT's EnvironmentReader.
Env holds a copy of the EnvironmentReader code to avoid dependency of
terminal to other CDT.
Change-Id: I8929bf427af99d3d62cca28ee8090aa423c9aded
Signed-off-by: jantje <eclipse@baeyens.it>