More symbol exports and C-API example
base/bool.jl: `-0.0 + false === -0.0`.
Fix jl_apply_array_type (root boxed dim)
Take git info out of BUILD_INFO, prepare for tarball export
Added source-dist make target

source-dist is a make target for creating a standalone tarball that can
be compilled on a system with the requisit external dependencies without
internet access to download the internal dependencies.
Changed BUILD_INFO to GIT_VERSION_INFO in methodsshow
remove explicit paths, and gnutar assumption
move tar check to Make.inc and update tar commands
test for compatible tar, error if not found
Skip unicode tests if `iconv --version` fails
Add instructions for windows users
Checked inn readline patches, instad of downloading them

I can not see why we download the readline patches, and it requires
somewhat  ugly code in the make rule for the source-dist target.
Define power function for Float16
add norm=... keyword argument to quadgk for changing the desired error norm (see JuliaLang/ODE.jl#7)
Use shared utf8proc library when USE_SYSTEM_UTF8PROC=1

Distribution policies strongly discourage statically linking
to libraries in packages. We thus need to allow using the
dynamic library when building packages.
windows: use full version for install dir (fixes #5541)
Merge pull request #5543 from ihnorton/fix5541

windows: use semver'd install dir (fixes #5541)
Merge pull request #5553 from nalimilan/utf8proc

Use shared utf8proc library when USE_SYSTEM_UTF8PROC=1
Merge pull request #5551 from JuliaLang/anj/power

Define power function for Float16
windows: manifest for 7zS.sfx

Setting `level="asInvoker"` in the SFX is necessary to avoid UAC.
All  other installer customization should be done with NSIS.