improve documentation of ConseqConv

Provide additional doc-files and cleanup ConseqConv.sig. The file
"ConseqConv.sig" changed considerably. However, the changes are just
reorderings and changed comments. The signature itself stayed unchanged.
Similarly, the changes to "ConseqConv.sml" are just changes to comments
and whitespace.

Expose CONSEQ_TOP_REWRITE_CONV and variants in ConseqConv

trailing newlines in *.{sml,sig} files from src/ removed

Trailing newlines from SML files in src/ were rendered in HTML documentation.

Remove trailing whitespace in source files.

Change src/bool to src/1 as a prelude to experimentation!