chore(proofcheck/checker/lexer.mll): fix space
fix(proofcheck/checker/smt2_cmd): skip assertion for trivial cases

 - (x <= +inf)
 - (-inf <= y)
fixup
fix(proofcheck/checker/ptree): verbose error msg for pruning
fix(proofcheck/checker/parser): add support inf
fix(proofcheck/checker/failhandler): handle special cases of find mid point of (-inf, inf)
fix(tools/proofcheck/checker/basic): output format