support ARRAY of ARRAY types

[jreadey]

Array types with an Array base type are not working.

E.g.:
{
"type": {
"class": "H5T_ARRAY",
"base": {
"class": "H5T_ARRAY",
"base": {
"class": "H5T_STRING",
"charSet": "H5T_CSET_ASCII",
"strPad": "H5T_STR_NULLPAD",
"length": 20
},
"dims": [ 49, 60, 124, 51, 48 ]
},
"dims": [ 49, 60, 124, 51, 48 ]
}