Add script generate_coverage_report for generating test coverage report using gcov and lcov

generate_coverage_report

@@ -0,0 +1,11 @@
+#!/bin/bash
+make clean
+rm -r coverage_report
+make test CXXFLAGS="-Wall -Wextra -pedantic -g -fprofile-arcs -ftest-coverage"
+gcov src/*.cpp -o src/
+lcov --directory ./ --capture --output-file lcov.info -b ./
+genhtml lcov.info -o coverage_report
+rm src/*.gcda
+rm src/*.gcno
+rm lcov.info
+make clean