established thy-ctxt strategy (1..2) for ME/mstools.sml

strategy in 2 steps:
(1) update isac to Isabelle2009-2 with minimal changes
(a) 'parse thy' left as is
'str2t' --> 'str2term_' according to (b)
'comp_dts thy' left as is, but returns term NOT cterm
(b) pretty printing '*2str' always without thy | ctxt
pretty printing '*2str_' always with ctxt
(2) make parsing dependent on context of calculation
(a) 'parse thy' --> 'parse ctxt' simplified by searchin 'thy'
(b) nothin to do

cleaned Script: rules2scr_Rls, rules2scr_Seq

changed \"plus\" -> \"PLUS\", times, power_, sqrt_, times_

with e.g find . -type f -exec sed -i s/\"divide_\"/\"DIVIDE\"/g {} \;
Respective updates in the Scripts need to be done by hand.

finished Script/*

TODO: replace "plus" -> "PLUS", times, power_ in calclist and scripts

new branch for adapting jEdit to isac

Added the Isac-jEdit-Nb-project

SD parser v.0 enhanced, 1 alternative missing

Added rules, which do not yet work in general.
To be done together with making alternative working.

version sufficient to start work on scala parsers.

v.0 of parser for Back's structured derivations, 1 alternative missing

clarified handling of Parse.term, resume parse SDs

established clean test files