Host some tool R code in share/jupyter/kernels/xr/R directory

[romainfrancois]

The idea here is to have a place where we can have some R code, instead of doing inlines as in e.g.

xeus-r/src/xinterpreter.cpp

Line 215 in 07de11d

const char* try_catch = ".xeus_try_catch <- function(expr) {.xeus_sys_calls <- NULL; tryCatch(withCallingHandlers(withVisible(eval(expr, globalenv())), error = function(condition){sys_calls <- sys.calls(); sys_calls <- sys_calls[seq(10, length(sys_calls))];.xeus_sys_calls <<- sys_calls}), error = function(condition) { structure(list(condition = condition, calls = .xeus_sys_calls, stack = capture.output(traceback(.xeus_sys_calls, max.lines = 1L)) ), class = 'xeus_error')})}";

which will quickly become error-prone and not easily maintainable.

This will be useful for e.g. #13

[romainfrancois]

This is a bit over the top, but the idea here is to figure out where xr is and then find the ../share/jupyter/kernels/xr/R/setup.R file and source() it.

Are there better ways to host extra files ?