Update C APIs

Full Changelog: v2.0.11...v2.0.12

Fix a bug in the case of removing all objects

Full Changelog: v2.0.10...v2.0.11

Update C APIs

Full Changelog: v2.0.9...v2.0.10

Fix uninitialized parameters for QG

Full Changelog: v2.0.8...v2.0.9

Fix the bug of the cosine similarity

v2.0.8

fix the bug of the cosine similarity

Fix minor bugs of QG and QBG

v2.0.7

fix minor bugs of QG and QBG

Update the way to specify the build parameters

v2.0.6

update the way to specify the build parameters

Add functions to QBG C APIs and some trivial updates

v2.0.5

add functions to QBG C APIs

Update setup.py to build ngtpy_qbg for QG and QBG

v2.0.4

update setup.py to build ngtpy_qbg for QG and QBG

Update setup.py to build ngtpy

v2.0.3

update setup.py to build ngtpy for a pypi distribution