Add coverage tests in main Makefile

Makefile

 PY_SRC:=$(wildcard dmt/asn2dataModel.py dmt/aadl2glueC.py dmt/smp2asn.py dmt/*mappers/[a-zA-Z]*py dmt/commonPy/[a-zA-Z]*py)
 PY_SRC:=$(filter-out dmt/B_mappers/antlr.main.py dmt/A_mappers/Stubs.py, ${PY_SRC})
 
-all:	flake8 pylint mypy
+all:	flake8 pylint mypy coverage
 
 flake8:
 	@echo Performing syntax checks via flake8...
@@ -15,4 +15,8 @@ mypy:
 	@echo Performing type analysis via mypy...
 	@mypy --check-untyped-defs ${PY_SRC} || exit 1
 
+coverage:
+	@echo Performing coverage checks...
+	@$(MAKE) -C tests-coverage  || exit 1
+
 .PHONY:	flake8 pylint mypy