doc/Loadtools-performance: removed the section about SREC programming With our current fc-loadtool there is no difference in performance between different flash programming commands, and the explanation of binary vs. S-record issues has been moved to the new Binary-file-formats and Flash-programming articles.

This host side library contains common modules for tools like fc-tmsh and
g23sh which operate asynchronously.  This code has been factored out of
fc-tmsh.