add support for diagnostics

[zwetan]

it would be useful to be able to list all the informations of Redtamarin

not only the version like we have with -v

but also list Redtamarin environment variables
for ex: REDTAMARIN_SDK=/usr/lib/redtamarin

and list the ABC libraries installed and their versions
for ex: $ redtamarin --show-libraries
and you would get

redtamarin  0.4.1
redbeanlib  1.0.3
httplib     1.0
ansilib     0.9
etc.

detect and list other SDK
like the Flex SDK, the AIR SDK

detect and list additional tools
like debian package helper

show a diagnostics info as
$ redtamarin --diagnostics
and get

you can compile ABC files       [✔]
you can create projectors       [✔] 
you can build with the AIR SDK  [✘]
some configuration problem      [⚠]