Fix warnings when printf'ing longs: use %ld, not %d
Fix compiler warning: missing header for php_info_*
Parameter checking: simply return on error, as is the idiom

if zend_parse_parameters() fails, it will print an error message saying
what kind of error occurred (maybe not enough parameters, maybe
parameters of the wrong type), and populate the return value with
`false`. What all the other extensions do in this situation, and what is
documented in the Oreilly PHP book, is to just return.

The current behavior is certainly wrong, because it will print a message
about wrong parameter counts regardless of what the real error is.
smbc_open: add open flags support just like fopen
smbclient_write: make write length optional just like fwrite

No need to pass a third argument to the function with the length of
string to write, when we already know the length of the string.
smbclient_unlink: recognize the EBUSY error

Encountered this error code (undocumented in the libsmbclient header)
when trying to unlink a file that was still open.
README: convert to Markdown, add function descriptions
smbclient_write: correct error messages, add EACCES

Error messages for smbclient_write were referring to reads for some
reason. Correct this. Also, during testing we encountered EACCES when
trying to write to a file opened for read-only. Handle that error code
properly.
Merge pull request #2 from aklomp/cleanup

libsmbclient: more cleanup work, documentation, slight API changes