extra semicolons removed from (some) .sig files

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

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

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Committing in a revised version of the quotients package, where now
erroneous input theorems are usually detected early, and the erroneous
theorem listed in an error message. This should greatly improve the
usability of the package, especially for new users. Thanks to Michael
Norrish for prodding me on this one.

Also added a new version of finite sets from lists, due to Michael Norrish.

Also moved the "obj" directory to now be called "sigma"; this contains
the sigma calculus example from Abadi and Cardelli, as described in the
longer 45-page paper.

Modified Files:
hol98/src/quotient/examples/finite_setScript.sml
hol98/src/quotient/src/quotient.sml
hol98/src/quotient/src/quotientScript.sml
Added Files:
hol98/src/quotient/examples/ext_finite_setScript.sml
hol98/src/quotient/examples/sigma/MutualIndThen.sig
hol98/src/quotient/examples/sigma/MutualIndThen.sml
hol98/src/quotient/examples/sigma/alphaScript.sml
hol98/src/quotient/examples/sigma/barendregt.sig
hol98/src/quotient/examples/sigma/barendregt.sml
hol98/src/quotient/examples/sigma/ind_rel.sig
hol98/src/quotient/examples/sigma/ind_rel.sml
hol98/src/quotient/examples/sigma/liftScript.sml
hol98/src/quotient/examples/sigma/more_listScript.sml
hol98/src/quotient/examples/sigma/more_setScript.sml
hol98/src/quotient/examples/sigma/objectScript.sml
hol98/src/quotient/examples/sigma/reductionScript.sml
hol98/src/quotient/examples/sigma/semanticsScript.sml
hol98/src/quotient/examples/sigma/tactics.sig
hol98/src/quotient/examples/sigma/tactics.sml
hol98/src/quotient/examples/sigma/variableScript.sml
Removed Files:
hol98/src/quotient/examples/obj/MutualIndThen.sig
hol98/src/quotient/examples/obj/MutualIndThen.sml
hol98/src/quotient/examples/obj/alphaScript.sml
hol98/src/quotient/examples/obj/barendregt.sig
hol98/src/quotient/examples/obj/barendregt.sml
hol98/src/quotient/examples/obj/ind_rel.sig
hol98/src/quotient/examples/obj/ind_rel.sml
hol98/src/quotient/examples/obj/liftScript.sml
hol98/src/quotient/examples/obj/more_listScript.sml
hol98/src/quotient/examples/obj/more_setScript.sml
hol98/src/quotient/examples/obj/objectScript.sml
hol98/src/quotient/examples/obj/reductionScript.sml
hol98/src/quotient/examples/obj/semanticsScript.sml
hol98/src/quotient/examples/obj/tactics.sig
hol98/src/quotient/examples/obj/tactics.sml
hol98/src/quotient/examples/obj/variableScript.sml
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