#1108: add option to find and use external sundials
#1108: can use external csparse
clean up external package logic
#1108: can use external tinyxml
re-enable debian tinyxml plugin
upgrade tinyxml to 2.6.2
#1108: external dsdp (broken until the interface is updated)
remove unneeded system sundials libraries
cmake: find dsdp after blas/lapack