Introduce CaseSensitivity enum class

The enum is a bit more verbose, but leads to more readable code:

str.Equals("foo", true)
// vs.
str.Equals("foo", CString::CaseSensitive)

Deprecate the old Equals() and leave out the length parameter
from the new version => use StartsWith() or StrCmp() instead.

include/znc/ZNCString.h

@@ -57,6 +57,11 @@ static const unsigned char base64_table[256] = {
 	XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX, XX,XX,XX,XX,
 };
 
+enum class CaseSensitivity {
+	CaseInsensitive,
+	CaseSensitive
+};
+
 /**
  * @brief String class that is used inside ZNC.
  *
@@ -75,6 +80,9 @@ public:
 		EDEBUG
 	} EEscape;
 
+	static const CaseSensitivity CaseSensitive = CaseSensitivity::CaseSensitive;
+	static const CaseSensitivity CaseInsensitive = CaseSensitivity::CaseInsensitive;
+
 	explicit CString(bool b) : std::string(b ? "true" : "false") {}
 	explicit CString(char c);
 	explicit CString(unsigned char c);
@@ -149,12 +157,15 @@ public:
 	/**
 	 * Check if this string is equal to some other string.
 	 * @param s The string to compare to.
-	 * @param bCaseSensitive True if you want the comparision to be case
-	 *                       sensitive.
-	 * @param uLen Number of characters to consider.
+	 * @param cs CaseSensitive if you want the comparision to be case
+	 *                       sensitive, CaseInsensitive (default) otherwise.
 	 * @return True if the strings are equal.
 	 */
-	bool Equals(const CString& s, bool bCaseSensitive = false, CString::size_type uLen = CString::npos) const;
+	bool Equals(const CString& s, CaseSensitivity cs = CaseInsensitive) const;
+	/**
+	 * @deprecated
+	 */
+	bool Equals(const CString& s, bool bCaseSensitive, CString::size_type uLen = CString::npos) const;
 	/**
 	 * Do a wildcard comparision between two strings.
 	 * For example, the following returns true: