With SSO implementation in String, StreamString::write generates wrong strings under some circumstances.
Reason is that String::len() returns strlen(sso_buf) if SSO=true but with newly written data (in StreamString::write) the null-termination missing at the time len() is called.
Furthermore, len() is called twice which is inefficient if SSO=true.
* Git ignore
* - StreamString fix
* Remove changes to gitignore
* Fix missing space for 0-terminator lost in conversion
Reduce String memory overhead from 24 bytes to 16 bytes by limiting the
maximum string length to <64Kbytes (which is larger than heap so no
effective problem).
Add Small String Optimization, SSO, which instead of allocating pointers
to small strings on the heap will store the string in place of the
pointer in the class. This should reduce memory fragmentation as
Save up to 12 chars (11 + \0) in String itself by using the terminating
\0 in the inline string as a flag to identify if this is a SSO or a heap
string.
Add a host test that verifies that no memory is allocated until a
full 11 characters are assigned to a string, as well as checking all
intermediate values.
No user code changes should be required to work with this optimization.
