adding the bash completition script for the client

contrib/lightning-cli.bash-completion

@@ -0,0 +1,48 @@
+# bash programmable completion for lncli
+# copy to /etc/bash_completion.d and restart your shell session
+# Copyright (c) by Andreas M. Antonopoulos
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+# modified by Tomas Stary (2018) for lightning-cli
+
+_lightning_cli() {
+    local cur prev words=() cword
+    local lightning_cli
+
+    # lightning_cli might not be in $PATH
+    lightning_cli="$1"
+
+    COMPREPLY=()
+    _get_comp_words_by_ref -n = cur prev words cword
+
+    case "$cur" in
+        -*=*)	# prevent nonsense completions
+            return 0
+            ;;
+        *)
+            local helpopts globalcmds
+
+
+            # get the global options, starting with --
+            if [[ -z "$cur" || "$cur" =~ ^- ]]; then
+                globalcmds=$($lightning_cli --help 2>&1 | awk '$1 ~ /^-/ { sub(/,/, ""); print $1}')
+            fi
+
+
+            # get the regular commands
+            if [[ -z "$cur" || "$cur" =~ ^[a-z] ]]; then
+		helpopts=$($lightning_cli help 2>/dev/null | awk '{print $4}' | sed 's@[,"]@@g')
+            fi
+
+            COMPREPLY=( $( compgen -W "$helpopts $globalcmds" -X "*," -- "$cur" ) )
+    esac
+} &&
+complete -F _lightning_cli lightning-cli
+
+# Local variables:
+# mode: shell-script
+# sh-basic-offset: 4
+# sh-indent-comment: t
+# indent-tabs-mode: nil
+# End:
+# ex: ts=4 sw=4 et filetype=sh