add DATAROOTDIR to build_h.jl, use it in Base.runtests()

Backport of 6f896703e43
from #8379
move default setting of prefix to Make.inc,

change SYSCONFDIR and DATAROOTDIR to be relative paths

Backport of: 3f4d2fca8
for #8379
Added fill() to manual/arrays

This is a combination of 3 commits
added fill() to manual/arrays
Backport of f466dfcc2bcde51755c9b7a9d58a484b55de8e48

added definite articles to fill! docs
Backport of b4e742cfed1884bab034e032e97ac17890f5c6f5

one more 'the' for fill
Backport of 6e685c31156b30632a7e40d9cb5f699f79c7546f
consistent formatting for show_unquoted

Backport of 63aa914886222b645e0c07575dbd52f268627174
for #8408
add show for typed comprehensions

Bacport of d926adee28476
from #8408
Fixed typos in splice! examples

Backport of b012c1c23f35fe882036baedddcd15e36fae4e9d
for #8437
Updated helpdb.jl
properly show transpose exprs

Backport of 495015e1f991ae9e69fa5e6b20047f6bbbe29400
for #8409
signbit returns bool, not int
Avoid more cases where signbit is treated as int

Backport of b32a48f5c4e09245f5985034c28908ac152c8da1
Backport of 8806a2d5548442c959528a62e6fe2910ed1b507e

for #8414
Docs: remove nonexistent Ccomplex_float, Ccomplex_double
Remove commented-out references to Ccomplex_* in Base

Backport of ce42b3e2916d45ed27364f804bb47ddc61022e62
and fb032123a89e3105a932f3cabfedab71d137edd4
Complete the description of Pkg.init()

Provides guidance for those wishing to implement a custom METADATA setup

Backport of 141da937e585d404906c69505bfe8fcf8af3d65d
for #8365
Removed failing show tests

These tests can apparently not be backported because they depend on an earlier fix to the printing system.

Commenting them out for now, so that travis can warn about more important stuff that might break.
move `reinterpret` error check inside `box`. fixes #8088

Conflicts:
	src/intrinsics.cpp
Backport of fd0075c68ea14ff and a small fix from 114e4dcefc4614
ref: #8088
fix issue #8155 where keywords arguments were not getting displayed properly

Backport of 370b640
for #8190
Merge pull request #8436 from nwh/release-0.3

backport for #8407, fixes to base/linalg/blas.jl
Formatting: use spaces instead of tabs for indentation
Add documentation on FFTW threads (relevant to #8455).

Backport of 58a1f48d7eba14f4b38fd32
Let's only run test/examples.jl if we can actually access the examples

Backport of 872d36349
from: #8466
fix #8464

backport of 94093ce161dd662f93659028c8d
Correct documentation for least squres \ and make documentation for elementwise operations more precise.