Initial public version of Manchester SSEM for SIMH

Initial public version of Manchester University Small Scale Experimental
Machine (SSEM) for SIMH
SSEM documentation added

Documentation added. Copyright information addedd/corrected.
Merge https://github.com/simh/simh
Added CR-LF line endings. Tabs replaced with spaces

Text files stored with CR-LF line endings, all tabs replaced with 4
spaces.
Merge https://github.com/simh/simh
LF endings replaced with CR-LF endings

Source file LF endings replaced with CR-LF endings. GIT configuration
changed: git config --global core.autocrlf false
Added build support for the new SSEM simulator and fixed minor compiler suggested cleanups