Micro string library: development stuff

 ustr (Micro string library) is a string API for C. It has tiny overhead over
 just plain strdup(), is much safer, is easier to use, is faster for many
 operations, can be used with read-only or automatically allocated data. You
 don't even need to link to the library to use it (so there are no
 dependencies).
 .
 This package contains header files and static library needed to compile code
 that uses ustr.