Adding a readme.

README.md

+# Table of content
+[[_TOC_]]
+
+# Description
+## Purpose
+The purpose of this device is to store variables as Tango attributes.
+
+## State
+The state is ON at the end of the initialization phase. It can be set later during the instance lifetime thru the command setState.
+
+## Status
+At the end of the init phase, the status displays the number of created attributes.
+
+# Properties
+## Definition
+The only property is `AttributesList`. Each line represents an attribute to create. The parameters are separated by the character `';'`.
+There is two possible configuration for an attribute:
+<ol>
+	<li>
+		By the name and full type:</li>
+		<ul>
+			<li>Attribute name</li>
+			<li>Attribute type as a string representing the type and format. [See the dedicated chapter](#attribute-full-type)</li>
+		</ul>
+	</li>
+	<li>
+		By the name and type and format. It allows to use more types.
+		<ul>
+			<li>Attribute name</li>
+			<li>
+				Attribute type. It can by set by a number or a string representing it. [See the dedicated chapter](#attribute-type-without-format)</li>
+			<li>
+				Attribute format. The possible values are:
+				<ul>
+					<li>SCALAR</li>
+					<li>SPECTRUM</li>
+					<li>IMAGE</li>
+				</ul>
+			</li>
+		</ul>
+	</li>
+</ol>
+
+## Attribute full type
+| Type       |Matching tango type |
+|:-----------|:-------------------|
+| int        | DevLong            |
+| long       | DevLong64          |
+| double     | DevDouble          |
+| float      | DevFloat           |
+| boolean    | DevBoolean         |
+| byte       | DevUChar           |
+| short      | DevShort           |
+| string     | DevString          |
+| devstate   | DeviceState        |
+| state      | DeviceState        |
+| devencoded | DevEncoded         |
+
+Adding `[]` turns the attribute to a spectrum, adding `[][]` turns it to an image. For example `double[]` will be a spectrum of DevDouble and `short\[][]` will be an image of short. Otherwise, the attribute will be a scalar.
+
+## Attribute type without format
+It can be set as a number or a string. The string value matches the tango type.
+
+| Number |Matching tango type |
+|:------:|:-------------------|
+| 1      | DevBoolean         |
+| 2      | DevShort           |
+| 3      | DevLong            |
+| 4      | DevFloat           |
+| 5      | DevDouble          |
+| 6      | DevUShort          |
+| 7      | DevULong           |
+| 8      | DevString          |
+| 23     | DevLong64          |
+| 24     | DevULong64         |
+| 22     | DevUChar           |
+| 19     | DeviceState        |
+| 28     | DevEncoded         |
+| 29     | DevEnum            |
+
+
+## Examples
+### Correct entries
+| Attribute definition | Resulting tango type     |
+|:--------------------:|:-------------------------|
+| attr1;1;SPECTRUM     | A spectrum of DevBoolean |
+| attr2;string         | A DevString scalar       |
+| attr3;double[]       | A spectrum of DevDouble  |
+
+### Wrong entries
+| Attribute definition    | Error                                                                                                                 |
+|:-----------------------:|:----------------------------------------------------------------------------------------------------------------------|
+| attr3;double[];SPECTRUM | This string definition doesn't require to specify the format. Use DevDouble, 5 or remove the format.                  |
+| attr3;double;SPECTRUM   | This string definition doesn't require to specify the format. Use DevDouble, 5 or remove the format and use double[]. |
+| attr4;5                 | If a number is used, the format must be specified.                                                                    |
+
+# Attributes
+All attributes are dynamically created from the property `AttributesList` in READ/WRITE mode and at operator level.
+
+# Initial values
+According to the type, the initial value will be zero for numerical values, false for booleans or empty for strings, spectrum and image.
+
+# Commands
+| Name       |Parameters                       | Description                                                                              |
+|:-----------|:--------------------------------|:-----------------------------------------------------------------------------------------|
+| Init       | None                            | Reinit the device. The properties will be parsed again and attributes will be recreated. |
+| state      | None                            | Returns the current state                                                                |
+| status     | None                            | Returns the current status                                                               |
+| setState   | A string representing the state | Sets the device state to the given value.<br/>Possible values are: <ul><li>ON</li><li>OFF</li><li>CLOSE</li><li>OPEN</li><li>INSERT</li><li>EXTRACT</li><li>MOVING</li><li>STANDBY</li><li>FAULT</li><li>INIT</li><li>RUNNING</li><li>ALARM</li><li>DISABLE</li><li>UNKNOWN</li></ul>.In upper case only. |
+