Adding multichannel examples

Adding multichannel examples in C,C++,C# and Java languages.
Adding waitsets C# example

Adding the source files in C# for waitsets example.
Adding sequences C# example

Adding sequences C# example and fixed one error from the another
languages
Adding dynamic data access union Java example

Adding dynamic_data_access_union_discriminator Java example
First version for java example.
Merge https://github.com/angelrti/rticonnextdds-examples
Added multichannel concept description to README.txt
New version dynamic_data_sequences java
dynamic_data_using_pub_sub java first version
Finished Dynamic_data_sequences java example
Finished DynamicData using publisher and subscriber Java example
Merge branch 'example/dynamic_data_pub_sub' into example/community
Multichannel examples to follow snake_case
Finished multichannel snake_case example
Added DynamicData C# examples
Added custom content filtered topic C# example
Fixed 80 columns by row
Added ordered_presentation C example
Fixed ordered.idl tabs
Added ordered_presentation C++ example