Make Swank load command for ECL with --load option

[susam]

Prior to this change, SlimvSwankLoader() builds the following Swank loader command for Embeddable Common-Lisp (ECL):

"ecl" -l "/home/susam/.vim/bundle/slimv/slime/start-swank.lisp"

The above command fails with the following error:

Unknown command line option -l.

As a result, when ,c is pressed in normal mode, Slimv fails to load Swank server. The correct option is --load instead. With this change, the following Swank loader command is built:

"ecl" --load "/home/susam/.vim/bundle/slimv/slime/start-swank.lisp"

With this loader command, when ,c is pressed in normal mode, Slimv is able to load Swank server successfully.

[susam]

Here is some information from my development environment to show that --load is indeed the correct option for Embedded Common Lisp (ECL).

$ cat /etc/debian_version 
10.1

$ head -n 1 /etc/os-release 
PRETTY_NAME="Debian GNU/Linux 10 (buster)"

$ ecl --version
ECL 16.1.3

$ ecl --help
Usage: ecl [-? | --help]
           [--dir dir] [--load file] [--shell file] [--eval expr] [--rc | --norc] [--hp | --nohp]
           [--c-stack size] [--lisp-stack size] [--heap-size size] [--frame-stack size]
           [[-o ofile] [-c [cfile]] [-h [hfile]] [--data [datafile]] [-s] [-q]
            --compile file]
           [[-o ofile] --link file+]
           [--input-encoding external-format] [--output-encoding external-format]
           [--error-encoding external-format] [--encoding external-format]
           [--trap-fpe | --no-trap-fpe]

$ man ecl | grep -A 1 -- --load
       [--dir dir] [--load file] [--shell file] [--eval expr]
       [--norc] [--hp | --nohp]
--
       --load file
                 Load source file before loading the .rc file and starting the Top Level.