packed: added unit tests for ascii_hex
packed/string.h: fix padding in ascii_hex method pack; hex_to_int is added but not plugged in yet
Merge branch 'master' of https://github.com/acfr/comma
packed: added unit test for exception thrown by hex_to_int; and small refactoring of names in unit tests
packed/string.h: implemented hex_from_int and refactored ascii_hex
packed: added typename T to all hex functions
packed: removed tests for three-character hex numbers
Merge branch 'master' of https://github.com/acfr/comma
packed/string.h: using memset to fill storage with padding in hex_from_int
Merge branch 'master' of https://github.com/acfr/comma