Fix some bugs found by CoverityScan
Fix bug ignoring --tips <T> value argument
Fix R graph axes in plotting scripts
Removed obsolete arguments from description
Check if requested hash size is zero
Pass copy of dBNodeBuffer instead of const ptr
Fix array offset with char warning
Improve inferedges status updates and help text
Report correct memory usage when using max kmer limit in cmd_mem.c
Added tests for kmer=63,95 and run on Travis CI
Missed travis script from previous commit
Added futil functions to open input files + check path extensions [skip CI]
ctx-clean: Fix user message
Add cmd_parse_arg_int32() + move cmd_print_mem() func definition
Fix missing path check in ctx-check [skip CI]
ctx-check: Fix issues with loading a single path
Don't need tmp memory to load single path file
Major re-write of path data structure and output format

 *WORK IN PROGRESS*

I've begun re-writing how we store path data. This should remove a large source
of bugs, simplify the code and enable others to use our output format.
The new output format uses a JSON header which is nice.

Added libs/cJSON library (MIT)

split code into subdirectories:
  src/global
  src/basic
  src/paths
  src/graph
  src/graph_paths
  src/tools
  src/commands
  src/main
Run checks in debug command, fix bugs found
Convert ctx_thread + graph_walker to new GPath

ctx_thread.c: Converted to new graph path file format
graph_walker.c: Coverted to new GPathFollow
gpath_save.c: add more info to header, including system info and commands used
generate_paths.c: store kmer length