Utils examples

[barrust]

• add examples of each utility library
• Minor changes to stringlib
  • Added s_append_alt that takes a pointer to a pointer to the string to append to; allowing for realloc to return the pointer.
• Minor change to bitarray - rename ba_reset_bitarray to ba_reset
• Update Makefile
• Update Readme

[codecov-io]

Codecov Report

Merging #20 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #20      +/-   ##
==========================================
+ Coverage    95.3%   95.32%   +0.01%     
==========================================
  Files           4        4              
  Lines         809      812       +3     
==========================================
+ Hits          771      774       +3     
  Misses         38       38

Impacted Files	Coverage Δ
src/timing.h	100% <ø> (ø)	⬆️
src/bitarray.c	100% <100%> (ø)	⬆️
src/stringlib.c	99.33% <100%> (ø)	⬆️