Call jl_atexit_hook via Python's exit handler

[tkf]

see also JuliaPy/PyCall.jl#603

[coveralls]

Pull Request Test Coverage Report for Build 527

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 75.093%

---

Files with Coverage Reduction	New Missed Lines	%
julia/core.py	5	81.89%

Totals
Change from base Build 525:	0.1%
Covered Lines:	606
Relevant Lines:	807

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 527

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 75.093%

---

Files with Coverage Reduction	New Missed Lines	%
julia/core.py	5	81.89%

Totals
Change from base Build 525:	0.1%
Covered Lines:	606
Relevant Lines:	807

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 528

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.1%) to 75.093%

---

Files with Coverage Reduction	New Missed Lines	%
julia/core.py	2	81.89%
julia/find_libpython.py	2	73.42%

Totals
Change from base Build 525:	0.1%
Covered Lines:	606
Relevant Lines:	807

---

💛 - Coveralls