Merge branch 'topic/file_case'

Merge branch 'topic/file_case'

* topic/file_case:
  Fix double delete for file_case usage..
  file_case review tweaks
  soelim(1): explicit request file_case::mux_unpack
  Many: use stdin support of file_case::muxer()
  file_case: add support for "-" a.k.a. stdin
  Preproc: use file_case::muxer() for ARGV: tbl/
  Preproc: use file_case::muxer() for ARGV: refer/
  Preproc: use file_case::muxer() for ARGV: preconv/
  Preproc: use file_case::muxer() for ARGV: pic/..
  Preproc: use file_case::muxer() for ARGV: html/
  Preproc: use file_case::muxer() for ARGV: grn/
  Preproc: use file_case::muxer() for ARGV: eqn/
  file_case: implement direct HAVE_ZLIB layer
  file_case: add read interface, extend abstraction..
  file_case: support transparent file decompression..
  Encapsulate searchpath:: FILE*'s in new class file_case
  src/include/lib.h: add some infrastructure