Reformatted code w.r.t. unifying code styles as of the official
CPPCoreGuidelines by Stroustrup and Sutter

Restructuring code w.r.t. configurations and definitions:
- #defines have been mostly removed from configurations
- a dedicated config file has been added for configurations with constexpr
- past configure file is now only a cmake wrapper
- wrapping global functions into namespaces

Removed all adafs and ifs occurrences. Now called gkfs

Write errors happenig on deamons are now reported back to clients.
"No space left on device" error is now properly propagated to clients.

margo context id is not the id of the host that send the request. Is the
internal context id of local margo instance.

 - improved statfs system call
 - intercepted statvfs library call

Both of the above function now report the aggregated real size
of all the data-nodes.

You can test this with `df "/tmp/gekkofs_mountpoint"` command

makes format of log messages more omogeneus

Implemented all the logic to handle truncate operation.

Test: added truncate test

In the daemon read handler manage read beyond end of file as normal case
and not exceptional

Acknowledge the main thread that the IO operation had terminate before
to actually close the file.

This is a "dirty" fix that waits to be refactored.

WARNING: Error on close will not be reported to the client that issued the IO
operation.

Data operation has been grouped under a ChunkStorage class
that will manage all the data backend operations.

The instance of this object is stored into the ADAFS_DATA sigleton.

The LRU map caused multiple issues with memory mappings and caused
severe errors and hanging situations. It has been replaced with a
std::map.

An Argobots mutex was added for rpc address lookups as many threads
might insert and lookup this map in parallel. This caused bulk_transfer
seqfauls as well as other file system crashes.

Cleanup of file system logging.

Before data was pulled first then written or read first and then pushed back

Only use 1 segment now but with multiple transfers