Merge branch 'sprint_18d' into 'master'

Implement kind parameter in floor()

See merge request lfortran/lfortran!1751

Merge branch 'pywrap' into 'master'

Functions implemented

See merge request lfortran/lfortran!1373

Merge branch 'llvm11' into 'master'

Interactive: implement complex types

See merge request lfortran/lfortran!1365

Merge branch 'f' into 'master'

LLVM: Pass values as a value

See merge request lfortran/lfortran!1357

Merge branch 'mailmap' into 'master'

Update mailmap

See merge request lfortran/lfortran!1201

Merge branch 'expr' into 'master'

Parser: fix precedence of .or. and .and.

See merge request lfortran/lfortran!1053

Merge branch 'attr-decl-chck' into 'master'

Check x.m_sym_type for null pointer

Closes lfortran#263

See merge request lfortran/lfortran!699

Merge branch 'nb' into 'master'

CI: show the evaluated notebook

See merge request lfortran/lfortran!643

Merge branch 'xeus5' into 'master'

Install the Jupyter kernel and execute notebooks

See merge request lfortran/lfortran!628

Merge branch 'nb3' into 'master'

Add a Demo2 notebook and a test for it

See merge request lfortran/lfortran!624