Bug 687576 - Add support for LATEX_EXTRA_STYLESHEET

Added the possibility for  LATEX_EXTRA_STYLESHEET analogous to  HTML_EXTRA_STYLESHEET. Special attention has been paid to the extension as ".sty" is automatically added by the \usepackage
Removed some comment statements.
Extra empty line in source fragments

In case of a language that does not uses curly brackets to define blocks (such as Fortran) there was a newline character in the variable c and this was written in the "code fragment" buffer and subsequently written to the output resulting in and extra empty line on top. I languages using curly brackets this is later overwritten by the while loop searching for the open curly bracket.
Support for INLINE_SOURCES in Fortran

Fortran does not yet support the INLINE_SOURCES, with this patch (part of) this omission is solved.
Fortran continuation character seen as begin of function call

In case in fixed format code a line like:
"     x   ( " existed and the x was on position 6 the "x   (" was seen as the start of a function call.
Fortran color code of END

The color for the single END in Fortran code was of the color of the flow type entities though for all the flow entities the entity name is mandatory. For the entity statements of some keywords e.g. SUBROUTINE and FUNCTION the entity name is not mandatory with the END statement. The color of the single END statement has been changed from the flow type to the normal keyword type.
Merge pull request #259 from albert-github/feature/bug_end_code_color

Fortran color code of END
Merge pull request #258 from albert-github/feature/bug_fortran_source_continuation

Fortran continuation character seen as begin of function call
Merge pull request #257 from albert-github/feature/bug_fortran_inline

Support for INLINE_SOURCES in Fortran
Merge pull request #256 from albert-github/feature/bug_first_line_inline

Extra empty line in source fragments
Merge pull request #253 from albert-github/feature/bug_687576

Bug 687576 - Add support for LATEX_EXTRA_STYLESHEET