fix: memory leaks in factorization
Merge pull request #367 from mmklee/memory_sw

fix: memory leaks in factorization
chg: remove pselect
fix: auto-set --cpus depending on machine
(cherry picked from commit a105120f52f4e741b4e7ce0e3c6054111859f429)

Signed-off-by: Andreas Steenpass <steenpass@mathematik.uni-kl.de>
chg: re-enable system("cpu"), change setting of semaphore 0
(cherry picked from commit 71871dcf30b201439f1a4885b5dd9f6ecd140938)

Signed-off-by: Andreas Steenpass <steenpass@mathematik.uni-kl.de>
fix: close in m2_end
(cherry picked from commit 3189a3707ba12fa2348a78276959d7cfd9155040)

Signed-off-by: Andreas Steenpass <steenpass@mathematik.uni-kl.de>

Conflicts:
	Singular/misc_ip.cc (trivial)
fix: race between sig_term)hdl and m2_end in closing links
(cherry picked from commit 8435d8916aad63d28f131509cd17cb1e915dc8f4)

Signed-off-by: Andreas Steenpass <steenpass@mathematik.uni-kl.de>

Conflicts:
	Singular/silink.h
	Singular/ssiLink.cc
    (files moved, but these changes have already been ported anyway)
fix: m2_end
(cherry picked from commit b42514daaae54b8e43c3334010886a29dc3c90d1)

Signed-off-by: Andreas Steenpass <steenpass@mathematik.uni-kl.de>
add: slPrepClose (prepare to close for ssiLinks)
(cherry picked from commit 3b238b30c58f096ed6cfbc6670d7291d3a0ff2e2)

Signed-off-by: Andreas Steenpass <steenpass@mathematik.uni-kl.de>

Conflicts:
	Singular/silink.cc
	Singular/silink.h
	Singular/ssiLink.cc
    (files moved, but these changes have already been ported anyway)
fix: how to close MP links
(cherry picked from commit 936767ca6428b3ef653f4ee26730f4d13ec394b3)

Signed-off-by: Andreas Steenpass <steenpass@mathematik.uni-kl.de>

Conflicts:
	Singular/mpsr_sl.cc (file deleted)
	Singular/silink.cc (file moved)

	Singular/silink.h
	Singular/ssiLink.cc
    (files moved, but these changes have already been ported anyway)
Merge pull request #369 from steenpass/changes_from_master

Changes from master
chg: removed ntl
removed unused CMakeLists.txt
chg: Z/n can be defined via integer,n for bigint n
chg: removed 'extern "C"' around declaration of feOptHelp and feGetOptValue

proposed fix from Hans
declaring functions as C functions caused some problems during the compilation
on cygwin systems because certain object files expected them to be c++ functions
unsure why they were declared as C functions to begin with
Merge pull request #370 from YueRen/spielwiese

chg: removed 'extern "C"' around declaration of feOptHelp and feGetOptValue
chg: improve definiteGcdCancellation by using singclap_gcd_and_divide
chg: handle nested fractions in singclap_gcd_and_divide
chg: updated test results
Merge pull request #371 from mmklee/cancellation

Cancellation