Ctrl-H shortcut to toggle hidden files' visibility

Signed-off-by: Lukas Hrazky <lukkash@email.cz>

# Please enter the commit message for your changes. Lines starting
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# On branch master
# Your branch is ahead of 'origin/master' by 9 commits.
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#	modified:   src/case.cpp
#	modified:   src/case.h
#	modified:   src/filelist.cpp
#	modified:   src/filelist.h
#	modified:   src/pane.cpp
#	modified:   src/pane.h
#
