dsolve: fix broken test

pi/4 should not be expected to convert to sym properly, otherwise this
test is fine.  Remove xtest.
xtest the 0.7.5 failures

Filed Issue #169
dsolve: redo comment header, sounded overly limited

This works great, no need to sell it short :)

Also, added the blowup problem as a nonlinear test case.
remove test from ilaplace, cite issue number for laplace xtest
Merge pull request #1 from cbm755/cbmedits

some edits