Infer CSV delimiter if it hasn't been set explicitly

Closes #141

docs/topics/reading-and-writing-to-file.md

@@ -435,11 +435,15 @@ $spreadsheet = $reader->load("sample.csv");
 
 #### Setting CSV options
 
-Often, CSV files are not really "comma separated", or use semicolon (;)
+Often, CSV files are not really "comma separated", or use semicolon (`;`)
 as a separator. You can instruct
 \PhpOffice\PhpSpreadsheet\Reader\Csv some options before reading a CSV
 file.
 
+The separator will be auto-detected, so in most cases it should not be necessary
+to specify it. But in cases where auto-detection does not fit the use-case, then
+it can be set manually.
+
 Note that \PhpOffice\PhpSpreadsheet\Reader\Csv by default assumes that
 the loaded CSV file is UTF-8 encoded. If you are reading CSV files that
 were created in Microsoft Office Excel the correct input encoding may

docs/topics/reading-files.md

@@ -523,15 +523,17 @@ CSV       | YES | HTML   | NO
 
 ### Pipe or Tab Separated Value Files
 
-The CSV loader defaults to loading a file where comma is used as the
-separator, but you can modify this to load tab- or pipe-separated value
-files using the `setDelimiter()` method.
+The CSV loader will attempt to auto-detect the separator used in the file. If it
+cannot auto-detect, it will default to the comma. If this does not fit your
+use-case, you can manually specify a separator by using the `setDelimiter()`
+method.
 
 ``` php
 $inputFileType = 'Csv';
 $inputFileName = './sampleData/example1.tsv';
 
-/**  Create a new Reader of the type defined in $inputFileType  **/ $reader = \PhpOffice\PhpSpreadsheet\IOFactory::createReader($inputFileType);
+/**  Create a new Reader of the type defined in $inputFileType  **/
+$reader = \PhpOffice\PhpSpreadsheet\IOFactory::createReader($inputFileType);
 /**  Set the delimiter to a TAB character  **/
 $reader->setDelimiter("\t");
 //    $reader->setDelimiter('|');