PFW: Parameter adaptation (platform interface)

BZ: 15069

Adaptation nodes have been added to integer parameter types in the structural
description.
They all convert values between a platform value and the actual parameter
value.
When a conversion node affects the definition of an integer type parameter,
its interface type becomes "double" (instead of integer).
For now only linear adaptation type is supported.

Linear adaptation:
=================
Linear adaptation nodes consists of the following attributes:
- slope numerator (double, default = 1)
- slope denominator (double, defult = 1)
- offset (signed integer, default = 0)
Conversions from user (platform) values to blackboard are done the follwing
way:
blackboard_value = user_value * slope_numerator / slope_denominator + offset

Change-Id: I00abe9ba5961d8e541b616225531bbc7c8b465b0
Signed-off-by: Patrick Benavoli <patrickx.benavoli@intel.com>
Reviewed-on: http://android.intel.com:8080/25407
Reviewed-by: Barthes, FabienX <fabienx.barthes@intel.com>
Tested-by: Barthes, FabienX <fabienx.barthes@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
diff --git a/parameter/Element.h b/parameter/Element.h
index af4fc33..0e592d6 100644
--- a/parameter/Element.h
+++ b/parameter/Element.h
@@ -103,6 +103,7 @@
     // Conversion utilities
     static string toString(uint32_t uiValue);
     static string toString(int32_t iValue);
+    static string toString(double dValue);
 
     // Checksum for integrity checks
     uint8_t computeStructureChecksum() const;