Release 0.4.1

• update slither report #192
• Fix/slither results #184
• fix input validation in BPool #180
• Fix/minor errors in dt template #183
• Fix/more tests for fixed rate #182
• Release/v0.4.0 #178
• prepare for release v0.4.1 8882903
• add slither report d10e346
• fix (#191) a09aa00