Add LEVEL #4 regression testing files which is dedicated to
VTC files in relation with bugs they help to reproduce.
At the date of this commit, all VTC files are LEVEL 4 VTC files.
Add a makefile target 'reg-tests' to run all regression testing file
found in 'reg-tests' directory.
Add reg-tests/lua/h00000.vtc first regression testing file for a LUA
fixed by f874a83 commit.