List 'scram' as a system requirement

[rakhimov]

This seems to be the way to define external software as a dependency.
On most platforms,
SCRAM is provided with 'scram' package with a package manager.

[jto888]

Thanks for interest in this problem, but for an R package this simply will not work as hoped. The user must install SCRAM on his system, and in Windows he has to set the location of the scram.exe on his PATH. These tasks cannot be performed by R.
This is my "lack of portability" concern. I have to give users much more instructions to use the package than most are wont to perform. If I could embed the scram core in an R package, then nothing other than loading the package into R is required by the user.
Not to mention the performance boost by keeping the call internal.

[rakhimov]

scram is completely portable and available on all major platforms.
sysreqs project seems to be working on automatically
resolving/installing external software dependencies
since this seems to be common for packages in CRAN as well.

It is only poor users on 'lousy' operating systems (Windows) without a sane package manager,
who have to deal with 'special' instructions.
As for the PATH variable modification, SCRAM installer currently prompts a simple choice to add
scram binary location to the path automatically.
There's no work to do for a user to achieve the PATH modification.
It doesn't event require a restart.