Prepare 2.6.4

prepare version 2.6.3

#317
Some interesting add has been done into the master since 2.6.2 in particular #139
so let's go out a new version to make it available on arduino library manager

Update library.properties

solve Arduino IDE library warnings

1. get rid of unrecognized category warning in Arduino IDE. It doesn't seem to support multiple categories
2. add esp8266 to the list of architctures to avoid warnings about incompatible architecture. This library works on esp8266

adding library.properties for arduino library manager

Merge pull request #5 from dmsherazi/master

Added a readme

Merged revision(s) 195 from trunk:

oops
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