improved context implementations to match assumptions made in Context

related to #268
removed bad overriden implementation of assignments which resulted in dcl x:int; x:= 2 to fail on an undefined value abort
Remove the `Chaos` basic action after a discussion with JCPWoodcock at
the June convergence workshop.
Kill an old (outdated) directory of the CML0 grammar in MediaWiki format
Merge commit '4fef4b885d7b6885b69bde88bea3d07b206b1d82' into jwc/base
#268 added test
Merge branch 'development' of https://github.com/symphonytool/symphony into acf
Removed Chaos action.
Fixes due to the bug Model checker failing test #272.
corrected tostring of guarded action
fix for #235 however, there is still a problem if the loop action is wrapped in double brackets loop =(( ... ))
added error message to the cli when a input file doesnt exist
This fixes the issue in #235 that occurs when multiple (( )) are used around the action. The fix removed all knowladge of updatable values from the delayed context once written and thereby makes any upstream changes visible. The initial values set in the creation of replicated nodes are changed such that it is made a constant (pass by value).

@joey-coleman please check, merge and close if fix is confirmed.
Merge remote-tracking branch 'origin/kel/base' into jwc/base
Merge remote-tracking branch 'origin/acf' into alrd
Merge remote-tracking branch 'origin/development' into alrd