This release includes:

• Remove invalid reference link from keywords.txt. See #3 thanks @per1234
• Fix some warnings
• Allow use of custom FatFs options file:
  Add a file named ffconf_custom.h in the sketch folder will be used instead of the default config (ffconf_default.h).
• Fix SD detect pin usage (no more harcoded in the core, sd_conf.h removed from the core)
• Fix issue when passing File object as an argument of a function (copy constructor)