unified request flow && external binding to LDAP (go-ldap#232)

* unified request flow && external binding to LDAP

* fix debug mode

* go.mod was added

Added check for ControlValue string check (go-ldap#213)

* Added check for controlvalue

* Fixed tests

Fix LDAP diagnostics message used as format string (go-ldap#208)

* Add GetLDAPError() tests

This patch adds a couple of tests for the `GetLDAPError()` function.

* Fix LDAP diagnostics message used as format string

The GetLDAPError()-function passes the `diagnosticMessage` error field
as the first parameter to `fmt.Errorf()`. If this message happens to
contain a `%`-character, Go will try to interpret it.

This doesn't directly lead to an error, but results in error messages
containing format string error codes. E.g.:

The error message "Detailed error message %" will result in the error
"Detailed error message %!(NOVERB)".

This patch fixes this by inserting a format string as the first
argument to `fmt.Errorf()`.

Add ldap.TLSConnectionState()

conn: Ensure 64-bit alignment for atomics on 32-bit platforms

Update tags for gopkg.in/ldap.v3

Merge pull request go-ldap#134 from judwhite/feature/fix-race (go-lda…

…p#141)

fix race conditions in conn.go

Merge pull request go-ldap#99 from liggitt/dn-comparison

Add comparison methods for DN/RDN/AttributeTypeAndValue

Merge pull request go-ldap#83 from liggitt/control_test

Fix control round-tripping, parsing

Merge pull request go-ldap#71 from liggitt/godoc-gofmt

Update godoc, add gofmt check