uniform treatment of all document markup commands: 'text' and 'txt' merely differ in LaTeX style;
discontinued obsolete 'txt_raw' (superseded by 'text_raw');
eliminated obsolete Outer_Syntax.markup (superseded by keyword kinds);
'text' and 'txt' no longer appear in Sidekick tree due to change of keyword kind;
changed tagging of diagnostic commands within proof;
src/Pure
src/FOL
src/HOL
src/ZF
src/CCL
src/CTT
src/Cube
src/FOLP
src/LCF
src/Sequents
src/Doc
src/Tools