Use semantic names for testcases.
Renamed test/1.ldl to test/init-decl.ldl.
Delete now-extraneous dbglog call.
Increase resilience of is* functions.

Also un-abbreviate their names.
Delete another extraneous dbglog call.
Change comment model.

Force start and close markers of long and nesting comments to be
character-wise opposites.

Changed lang-comment-spec to take two or three chars, M, L, and N,
rather than three or five. Now target syntaxes have:
line-comment = <M M>
long-comment = <M L> ... <L M>
nest-comment = <M N> ... <N M> [optional]

Source language has M='#', L='-', and N=undefined.

Made test/init-decl.ldl test comments.

Also deleted an extraneous console.log call.