add iosys_repr and set default repr to short form #920

Job	Run time
Py3.10; no Slycot; no Pandas; no CVXOPT	5m 32s
Py3.10; no Slycot; no Pandas; conda CVXOPT	5m 39s
Py3.10; conda Slycot; no Pandas; no CVXOPT	5m 41s
Py3.10; conda Slycot; no Pandas; conda CVXOPT	5m 59s
Py3.12; no Slycot; no Pandas; no CVXOPT	5m 59s
Py3.12; no Slycot; no Pandas; conda CVXOPT	6m 24s
Py3.12; conda Slycot; no Pandas; no CVXOPT	6m 18s
Py3.12; conda Slycot; no Pandas; conda CVXOPT	6m 56s
Py3.12; conda Slycot; conda Pandas; conda CVXOPT ; QtAgg	6m 38s
Finalize parallel coveralls	2s
	55m 8s

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