Merge branch '1755_code_cleanup'
* 1755_code_cleanup:
Doc cleanup: removed description of removed editor option.
Added shortcuts for CmdInfo (C-x i) and CmdQuickView (C-x q) commands.
Fixed Arch packages description in Syntax file.
Cleanup of code for compile with new warnings options for compilator
Added macros for simplest debug process (yes, gdb is a better way)
Reorganization of src/Makefile.am
Now possible to compile mc in different cases: as mc maintainer or as end-user.
Added checks for compiler options.
Ticket #1755: code cleanup before 4.7.0-pre4 release.