eliminate command

[parisse]

eliminate in Xcas is based on an efficient Groebner basis engine that can handle double reverse lexicographic ordering (by double I mean order first with respect to the variables to be eliminated then with respect to other variables). I optimized this Groebner code several years for 64 bit processors. And unfortunately it fails on the arm 32 bits processor of the Prime, I made a check and it crashes on the Prime G1 (at least)/ I do not have an emulator where I could try to fix that efficiently (the hp "emulator" is not a real emulator, it is a simulator, it is using code compiled for amd64/x64 not for arm). This is sad, but running code calling Groebner basis code on a calculator is not recommended anyway because it would require large amount of RAM even for simple inputs...