doc: Update more docstrings to have one sentence summary as first line. Reviewed io, java, linear-algebra, prefs, and set script directories. * scripts/io/beep.m, scripts/io/dlmwrite.m, scripts/io/importdata.m, scripts/io/strread.m, scripts/io/textread.m, scripts/java/javaArray.m, scripts/java/java_get.m, scripts/java/java_set.m, scripts/java/javaaddpath.m, scripts/java/javachk.m, scripts/java/javaclasspath.m, scripts/java/javamem.m, scripts/java/javarmpath.m, scripts/linear-algebra/bandwidth.m, scripts/linear-algebra/commutation_matrix.m, scripts/linear-algebra/cond.m, scripts/linear-algebra/condest.m, scripts/linear-algebra/cross.m, scripts/linear-algebra/duplication_matrix.m, scripts/linear-algebra/expm.m, scripts/linear-algebra/housh.m, scripts/linear-algebra/isdefinite.m, scripts/linear-algebra/ishermitian.m, scripts/linear-algebra/issymmetric.m, scripts/linear-algebra/istril.m, scripts/linear-algebra/istriu.m, scripts/linear-algebra/krylov.m, scripts/linear-algebra/logm.m, scripts/linear-algebra/normest.m, scripts/linear-algebra/null.m, scripts/linear-algebra/onenormest.m, scripts/linear-algebra/orth.m, scripts/linear-algebra/qzhess.m, scripts/linear-algebra/rank.m, scripts/linear-algebra/rref.m, scripts/linear-algebra/vech.m, scripts/path/matlabroot.m, scripts/prefs/addpref.m, scripts/prefs/getpref.m, scripts/prefs/ispref.m, scripts/prefs/rmpref.m, scripts/prefs/setpref.m, scripts/set/powerset.m, scripts/set/setdiff.m: Update more docstrings to have one sentence summary as first line.

syntax: regexp
# The recurrent (^|/) idiom in the regexps below should be understood
# to mean "at any directory" while the ^ idiom means "from the
# project's top-level directory".

# gnulib makes these silly backup files
.~$

# This directory gets created by gnulib during the build. 
# It contains no Octave files.
^libgnu/*

# This directory mostly contains cruft during build time, but it does
# contain some Octave code, so we gotta be a bit more careful about
# what we ignore here
^m4/(?!ax_).+\.m4$

# Emacs tools create these
(^|/)TAGS$
(^|/)semantic.cache$

(/|^)Makefile\.in$
^INSTALL$

^aclocal\.m4$
^build-.*($|/)
^configure$
^autom4te\.cache($|/)
^config\.in\.h$

# e.g. doc/faq/OctaveFAQ.info
#      doc/interpreter/octave.info-4
^doc/.*\.info(-\d)?$

^doc/\w*/stamp-vti$
^doc/\w*/version\.texi$
^doc/interpreter/images\.mk$

# e.g. liboctave/operators/smx-op-inc.mk
^liboctave/operators/\w+-op-\w+\.mk$

^libinterp/dldfcn/module\.mk$