Merge branch '2888_cleanup'

Merge branch '2888_cleanup'

* 2888_cleanup: (30 commits)
  Refactoring of endless loops and some type accuracy.
  Refactoring of subshell support.
  Remove stub environment file from tests
  make internal library for testing purposes
  remove src/main.h file
  Move global variables to an appropriate place
  move do_load_prompt() and load_prompt() from src/main.c to src/filemanager/layout.c
  move do_cd from src/main.c to src/filemanager/panel.c
  mcedit: type accuracy in block operation routines.
  Fix of sys/ioctl.h includes: use HAVE_SYS_IOCTL_H guard.
  Optimization of SIGWINCH handling.
  src/filemanager/Makefile.am: cleanup source file list.
  Clarify of i18n initialization.
  Rename _syntax_marker to syntax_marker_t and reimplement it using GSList.
  (compare_word_to_right): minor refactoring.
  Fix types for line numbers and byte offsets in syntax highlighting engine.
  Many editor functions: take editor as constant object.
  (get_first_editor_line): minor refactoring.
  (edit_get_syntax_color): return color directly.
  Rename syntax_rule to edit_syntax_rule_t.
  ...