typedefs for size_t in WIN and non-WIN, re #8912
Bring back changes lost in conflicts, re #8912

This fixes an issue in MantidPlot1DPlotTest which luckily reveal the loss of some chunks
typedef unsigned int size_t out, crashes on linux, re #8912
Merge branch 'feature/8912_CLI_new_branch_to_solve_conflicts' into develop