The two File classes have been enclosed into different namespaces.
To guarantee compatibility with old sketches that uses only one of the two
libraries an additional line:
using namespace xxxxx;
has been added so the users can still use "File" where there is no ambiguity.
BridgeLib::File and SDLib::File classes have been also aliased to BridgeFile
and SDFile respectively, users are encouraged to use that instead of File.
The SDClass class makes a reference to "SD.card" instead of just "card". SD is a global instance of SDClass.
This prevents any other instance of SDClass from functioning correctly.
The fix also allows SDClass to be used with an SD card which is removed and replaced, whereas previously, using the global instance SD did not allow this due to the limitation of begin() which cannot be called more than once.
