merge libmaple docs ("leaflabs-docs") into ./docs

In the past, libample documentation was forked out of this repository
because the documentation had increased in scope. For the librambutan,
and the rambutan project in general, we will try to keep documentation
closer to the source code, so the librambutan-specific documentation
should live here. Other sections of leaflabs-docs will be culled in a
following commit.

This merge attempts to maintain history by using a subtree strategy.
Followed directions at:

    http://nuclearsquid.com/writings/subtree-merging-and-you/

Full history for files should be accessible using the "--follow" flag to
git log, eg:

    git log --follow docs/source/adc.rst

It should be possible to pull patches from leaflabs-docs with:

    git pull -s subtree leaflabs-docs master

... at least until the docs in this repository diverge significantly.

1 files changed, 46 insertions, 0 deletions

diff --git a/docs/source/lang/cpp/double.rst b/docs/source/lang/cpp/double.rst
new file mode 100644
index 0000000..59422eb
--- /dev/null
+++ b/docs/source/lang/cpp/double.rst
@@ -0,0 +1,46 @@
+.. _lang-double:
+
+``double``
+==========
+
+Double precision floating point type. Occupies 8 bytes.  On Maple, the
+``double`` type has a range of approximately -1.79769×10^308 to
+1.79769×10^308; the ``double`` type subject to the same :ref:`overflow
+issues <lang-variables-rollover>` as any numeric data type.
+
+Floating point numbers are not exact, and may yield strange results
+when compared. For example ``6.0 / 3.0`` may not equal ``2.0``. You
+should instead check that the absolute value of the difference between
+the numbers is less than some small number.
+
+Floating point math is also much slower than integer math in
+performing calculations, so should be avoided if, for example, a loop
+has to run at top speed for a critical timing function.  Programmers
+often go to some lengths to convert floating point calculations to
+integer math to increase speed.
+
+For more information, see the `Wikipedia article on floating point
+math <http://en.wikipedia.org/wiki/Floating_point>`_\ .
+
+Floating-point numbers represent numbers with "decimal point", unlike
+integral types, which always represent whole numbers. Floating-point
+numbers are often used to approximate analog and continuous values
+because they have greater resolution than integers.
+
+The double implementation on the Maple uses twice the number of bytes
+as a :ref:`float <lang-float>`, with the corresponding gains in
+precision.
+
+Tip
+---
+
+Users who borrow code from other sources that includes ``double``
+variables may wish to examine the code to see if the implied range and
+precision are different from that actually achieved on the Maple.
+
+See Also
+--------
+
+-  :ref:`float <lang-float>`
+
+.. include:: /arduino-cc-attribution.txt