Remove outdated size tweak from performance tips section of manual
Merge pull request #7562 from JuliaLang/sjk/perf-tips

Remove outdated size tweak from performance tips section of manual
Merge branch 'master' of github.com:JuliaLang/julia
fix #7564

this is a combination of convert(Rational{T},x) not returning the
correct type, and the lack of a type check in codegen for new().
fix gemv! and gemm! in empty cases. fixes #7571

should always mutate, not sometimes return a new array
update helpdb
Update NEWS.md

Includes missing cross-references and minor formatting changes.
remove 0.2 deprecations and update one old precompile directive.
Add faster cumsum and cumprod to NEWS.
Merge branch 'print_evaluated_tests' of github.com:sjkelly/julia into print_evaluated_tests