Add config g:table_mode_ignore_align. Fix #145

* Disabled by default, if enabled directs table mode to ignore aligning
  based on alignment characters on the header and always left aligns

doc/table-mode.txt

@@ -1,7 +1,7 @@
 *table-mode.txt*			Table Mode for easy table formatting
 ===============================================================================
 	Table Mode, THE AWESOME AUTOMATIC TABLE CREATOR & FORMATTER
-                               VERSION 4.7.5
+                               VERSION 4.7.6
 
 		Author: Dhruva Sagar <http://dhruvasagar.com/>
 		License: MIT <http://opensource.org/licenses/MIT/>
@@ -78,6 +78,7 @@ Manipulation of tables:
         using |table-mode-insert-column-before-map| or after the cusor using
 	|table-mode-insert-column-after-map|.
 
+                                                              *table-formulas*
 Table Formulas:
 	Table Mode now has support for formulas like a spreadsheet. There
 	are 2 ways of defining formulas :
@@ -100,6 +101,7 @@ Table Formulas:
 	You can evaluate the formula line using |:TableEvalFormulaLine| or the
 	mapping |<Leader>tfe| defined by the option |table-mode-expr-calc-map|
 
+                                                         *formula-expressions*
 Formula Expressions :
 	Expressions are of the format '$target = formula'.
 
@@ -187,6 +189,7 @@ Overview:
         |table-mode-auto-align| ......... Set if the table mode should auto
                                         align as you type
         |table-mode-tableize-auto-border| Set if tableize adds row borders
+        |table-mode-ignore-align| ....... Set to ignore alignment characters
 
 g:loaded_table_mode					*table-mode-loaded*
 	Use this option to disable the plugin: >
@@ -376,6 +379,12 @@ g:table_mode_tableize_auto_border
         Enables adding row borders to tables when created using tableize. >
                 let g:table_mode_tableize_auto_border = 0
 <
+                                                       *table-mode-ignore-align*
+g:table_mode_ignore_align
+        If enabled, ignores alignment characters on the header border and always
+        left aligns. >
+                let g:table_mode_ignore_align = 0
+<
 
 ===============================================================================
 MAPPINGS						*table-mode-mappings*