Generalize convert for dict

The convert function's second argument can be any associative type, not just another dict, so it should be written more generally.
Merge pull request #8686 from StephenVavasis/patch-11

Generalize convert for dict
fix #8678, reading large files on windows

read() on windows takes a uint, so apply a similar io limit per call
as done on mac (directly reusing the same code would give a compiler
warning, since long is 32 bits on windows)
Merge pull request #8689 from JuliaLang/tk/fix8678

fix #8678, reading large files on windows
doc: Remove reference to deprecated 'dense' function
Merge pull request #8691 from julian-gehring/patch-doc-dense

doc: Remove reference to deprecated 'dense' function
Better function cross-referencing for Arrays chapter
Fix #4933
Fix #8570 and add test.
add missing precompile
Remove non-existent `tofirst` and `tolast` methods from adjuster API in Dates docs
Add documentation for Dates types
x::Int8=1000 now throws an error upon conversion
Fix leading_ones example
Tweak None == Union() discussion to reflect 0.4 behavior.
Merge pull request #8659 from JuliaLang/cjh/doc-types

Update type docs to 0.4-dev