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, 52 insertions, 0 deletions

diff --git a/docs/source/lang/cpp/enum.rst b/docs/source/lang/cpp/enum.rst
new file mode 100644
index 0000000..b6409eb
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+++ b/docs/source/lang/cpp/enum.rst
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+.. highlight:: cpp
+
+.. _lang-enum:
+
+``enum``
+========
+
+The ``enum`` keyword is used to specify an enumeration type.  An
+enumeration type is a type whose values are taken from a specified,
+fixed list of constant values.
+
+Example
+-------
+
+Here's an example defining an enumeration type called ``weather``,
+which has values ``HOT``, ``COMFY``, and ``COLD``::
+
+    enum weather {HOT, COMFY, COLD};
+
+Once you've defined this type, you can create variables of type
+``weather``, in the same way you would with an :ref:`int <lang-int>`::
+
+    // create a weather variable named theWeather, with value COMFY:
+    weather theWeather = COMFY;
+
+Enumeration types are useful within :ref:`switch statements
+<lang-switchcase>`.  If you know that an argument is of an enumeration
+type, you can make ``case`` statements for all of that type's possible
+values, so you know you won't miss anything::
+
+    void describeWeather(weather currentWeather) {
+        switch(currentWeather) {
+        case HOT:
+            SerialUSB.println("it's hot out");
+            break;
+        case COMFY:
+            SerialUSB.println("it's nice today");
+            break;
+        case COLD:
+            SerialUSB.println("it's freezing!");
+            break;
+        }
+    }
+
+Such a ``switch`` statement would need no :ref:`default
+<lang-switchcase-default>`, since we know that ``currentWeather`` must
+be either ``HOT``, ``COMFY``, or ``COLD``.
+
+See Also
+--------
+
+- :ref:`lang-switchcase`