Feature/pyconn: fix describe tables bugs which will cause the wrong length info of binary/nchar

Hotfix/fixbug query

fix insert/nchar-unicode.py case.

TD-617: fix some coverity issues

[TD-669] wrong errno while drop column from normal table

[TD-669] incomplete update while alter vgroup

invalid refcount calc while alter table

modify general/parser/stream.sim to make its result consistent.

[add sim case]

[TD-350]: add filter test cases for range

[TD-642]

When modifying the table schema, the calculation of memory size is wrong

[modify]

sdb write queue

fixbug revealed by coverity

# Conflicts:
#	tests/script/jenkins/basic.txt

Hotfix/test

fix TD-645, TD-660

Hotfix/td 628